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mariadb/storage/innobase/buf/buf0lru.cc
Marko Mäkelä 685d958e38 MDEV-14425 Improve the redo log for concurrency 
The InnoDB redo log used to be formatted in blocks of 512 bytes.
The log blocks were encrypted and the checksum was calculated while
holding log_sys.mutex, creating a serious scalability bottleneck.

We remove the fixed-size redo log block structure altogether and
essentially turn every mini-transaction into a log block of its own.
This allows encryption and checksum calculations to be performed
on local mtr_t::m_log buffers, before acquiring log_sys.mutex.
The mutex only protects a memcpy() of the data to the shared
log_sys.buf, as well as the padding of the log, in case the
to-be-written part of the log would not end in a block boundary of
the underlying storage. For now, the "padding" consists of writing
a single NUL byte, to allow recovery and mariadb-backup to detect
the end of the circular log faster.

Like the previous implementation, we will overwrite the last log block
over and over again, until it has been completely filled. It would be
possible to write only up to the last completed block (if no more
recent write was requested), or to write dummy FILE_CHECKPOINT records
to fill the incomplete block, by invoking the currently disabled
function log_pad(). This would require adjustments to some logic around
log checkpoints, page flushing, and shutdown.

An upgrade after a crash of any previous version is not supported.
Logically empty log files from a previous version will be upgraded.

An attempt to start up InnoDB without a valid ib_logfile0 will be
refused. Previously, the redo log used to be created automatically
if it was missing. Only with with innodb_force_recovery=6, it is
possible to start InnoDB in read-only mode even if the log file
does not exist. This allows the contents of a possibly corrupted
database to be dumped.

Because a prepared backup from an earlier version of mariadb-backup
will create a 0-sized log file, we will allow an upgrade from such
log files, provided that the FIL_PAGE_FILE_FLUSH_LSN in the system
tablespace looks valid.

The 512-byte log checkpoint blocks at 0x200 and 0x600 will be replaced
with 64-byte log checkpoint blocks at 0x1000 and 0x2000.

The start of log records will move from 0x800 to 0x3000. This allows us
to use 4096-byte aligned blocks for all I/O in a future revision.

We extend the MDEV-12353 redo log record format as follows.

(1) Empty mini-transactions or extra NUL bytes will not be allowed.
(2) The end-of-minitransaction marker (a NUL byte) will be replaced
with a 1-bit sequence number, which will be toggled each time when the
circular log file wraps back to the beginning.
(3) After the sequence bit, a CRC-32C checksum of all data
(excluding the sequence bit) will written.
(4) If the log is encrypted, 8 bytes will be written before
the checksum and included in it. This is part of the
initialization vector (IV) of encrypted log data.
(5) File names, page numbers, and checkpoint information will not be
encrypted. Only the payload bytes of page-level log will be encrypted.
The tablespace ID and page number will form part of the IV.
(6) For padding, arbitrary-length FILE_CHECKPOINT records may be written,
with all-zero payload, and with the normal end marker and checksum.
The minimum size is 7 bytes, or 7+8 with innodb_encrypt_log=ON.

In mariadb-backup and in Galera snapshot transfer (SST) scripts, we will
no longer remove ib_logfile0 or create an empty ib_logfile0. Server startup
will require a valid log file. When resizing the log, we will create
a logically empty ib_logfile101 at the current LSN and use an atomic rename
to replace ib_logfile0 with it. See the test innodb.log_file_size.

Because there is no mandatory padding in the log file, we are able
to create a dummy log file as of an arbitrary log sequence number.
See the test mariabackup.huge_lsn.

The parameter innodb_log_write_ahead_size and the
INFORMATION_SCHEMA.INNODB_METRICS counter log_padded will be removed.

The minimum value of innodb_log_buffer_size will be increased to 2MiB
(because log_sys.buf will replace recv_sys.buf) and the increment
adjusted to 4096 bytes (the maximum log block size).

The following INFORMATION_SCHEMA.INNODB_METRICS counters will be removed:

os_log_fsyncs
os_log_pending_fsyncs
log_pending_log_flushes
log_pending_checkpoint_writes

The following status variables will be removed:

Innodb_os_log_fsyncs (this is included in Innodb_data_fsyncs)
Innodb_os_log_pending_fsyncs (this was limited to at most 1 by design)

log_sys.get_block_size(): Return the physical block size of the log file.
This is only implemented on Linux and Microsoft Windows for now, and for
the power-of-2 block sizes between 64 and 4096 bytes (the minimum and
maximum size of a checkpoint block). If the block size is anything else,
the traditional 512-byte size will be used via normal file system
buffering.

If the file system buffers can be bypassed, a message like the following
will be issued:

InnoDB: File system buffers for log disabled (block size=512 bytes)
InnoDB: File system buffers for log disabled (block size=4096 bytes)

This has been tested on Linux and Microsoft Windows with both sizes.

On Linux, only enable O_DIRECT on the log for innodb_flush_method=O_DSYNC.
Tests in 3 different environments where the log is stored in a device
with a physical block size of 512 bytes are yielding better throughput
without O_DIRECT. This could be due to the fact that in the event the
last log block is being overwritten (if multiple transactions would
become durable at the same time, and each of will write a small
number of bytes to the last log block), it should be faster to re-copy
data from log_sys.buf or log_sys.flush_buf to the kernel buffer,
to be finally written at fdatasync() time.

The parameter innodb_flush_method=O_DSYNC will imply O_DIRECT for
data files. This option will enable O_DIRECT on the log file on Linux.
It may be unsafe to use when the storage device does not support
FUA (Force Unit Access) mode.

When the server is compiled WITH_PMEM=ON, we will use memory-mapped
I/O for the log file if the log resides on a "mount -o dax" device.
We will identify PMEM in a start-up message:

InnoDB: log sequence number 0 (memory-mapped); transaction id 3

On Linux, we will also invoke mmap() on any ib_logfile0 that resides
in /dev/shm, effectively treating the log file as persistent memory.
This should speed up "./mtr --mem" and increase the test coverage of
PMEM on non-PMEM hardware. It also allows users to estimate how much
the performance would be improved by installing persistent memory.
On other tmpfs file systems such as /run, we will not use mmap().

mariadb-backup: Eliminated several variables. We will refer
directly to recv_sys and log_sys.

backup_wait_for_lsn(): Detect non-progress of
xtrabackup_copy_logfile(). In this new log format with
arbitrary-sized blocks, we can only detect log file overrun
indirectly, by observing that the scanned log sequence number
is not advancing.

xtrabackup_copy_logfile(): On PMEM, do not modify the sequence bit,
because we are not allowed to modify the server's log file, and our
memory mapping is read-only.

trx_flush_log_if_needed_low(): Do not use the callback on pmem.
Using neither flush_lock nor write_lock around PMEM writes seems
to yield the best performance. The pmem_persist() calls may
still be somewhat slower than the pwrite() and fdatasync() based
interface (PMEM mounted without -o dax).

recv_sys_t::buf: Remove. We will use log_sys.buf for parsing.

recv_sys_t::MTR_SIZE_MAX: Replaces RECV_SCAN_SIZE.

recv_sys_t::file_checkpoint: Renamed from mlog_checkpoint_lsn.

recv_sys_t, log_sys_t: Removed many data members.

recv_sys.lsn: Renamed from recv_sys.recovered_lsn.
recv_sys.offset: Renamed from recv_sys.recovered_offset.
log_sys.buf_size: Replaces srv_log_buffer_size.

recv_buf: A smart pointer that wraps log_sys.buf[recv_sys.offset]
when the buffer is being allocated from the memory heap.

recv_ring: A smart pointer that wraps a circular log_sys.buf[] that is
backed by ib_logfile0. The pointer will wrap from recv_sys.len
(log_sys.file_size) to log_sys.START_OFFSET. For the record that
wraps around, we may copy file name or record payload data to
the auxiliary buffer decrypt_buf in order to have a contiguous
block of memory. The maximum size of a record is less than
innodb_page_size bytes.

recv_sys_t::parse(): Take the smart pointer as a template parameter.
Do not temporarily add a trailing NUL byte to FILE_ records, because
we are not supposed to modify the memory-mapped log file. (It is
attached in read-write mode already during recovery.)

recv_sys_t::parse_mtr(): Wrapper for recv_sys_t::parse().

recv_sys_t::parse_pmem(): Like parse_mtr(), but if PREMATURE_EOF would be
returned on PMEM, use recv_ring to wrap around the buffer to the start.

mtr_t::finish_write(), log_close(): Do not enforce log_sys.max_buf_free
on PMEM, because it has no meaning on the mmap-based log.

log_sys.write_to_buf: Count writes to log_sys.buf. Replaces
srv_stats.log_write_requests and export_vars.innodb_log_write_requests.
Protected by log_sys.mutex. Updated consistently in log_close().
Previously, mtr_t::commit() conditionally updated the count,
which was inconsistent.

log_sys.write_to_log: Count swaps of log_sys.buf and log_sys.flush_buf,
for writing to log_sys.log (the ib_logfile0). Replaces
srv_stats.log_writes and export_vars.innodb_log_writes.
Protected by log_sys.mutex.

log_sys.waits: Count waits in append_prepare(). Replaces
srv_stats.log_waits and export_vars.innodb_log_waits.

recv_recover_page(): Do not unnecessarily acquire
log_sys.flush_order_mutex. We are inserting the blocks in arbitary
order anyway, to be adjusted in recv_sys.apply(true).

We will change the definition of flush_lock and write_lock to
avoid potential false sharing. Depending on sizeof(log_sys) and
CPU_LEVEL1_DCACHE_LINESIZE, the flush_lock and write_lock could
share a cache line with each other or with the last data members
of log_sys.

Thanks to Matthias Leich for providing https://rr-project.org traces
for various failures during the development, and to
Thirunarayanan Balathandayuthapani for his help in debugging
some of the recovery code. And thanks to the developers of the
rr debugger for a tool without which extensive changes to InnoDB
would be very challenging to get right.

Thanks to Vladislav Vaintroub for useful feedback and
to him, Axel Schwenke and Krunal Bauskar for testing the performance.
2022-01-21 16:03:47 +02:00

1457 lines
43 KiB
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/*****************************************************************************
Copyright (c) 1995, 2016, Oracle and/or its affiliates. All Rights Reserved.
Copyright (c) 2017, 2022, MariaDB Corporation.
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA
*****************************************************************************/
/**************************************************//**
@file buf/buf0lru.cc
The database buffer replacement algorithm
Created 11/5/1995 Heikki Tuuri
*******************************************************/
#include "buf0lru.h"
#include "fil0fil.h"
#include "btr0btr.h"
#include "buf0buddy.h"
#include "buf0buf.h"
#include "buf0flu.h"
#include "buf0rea.h"
#include "btr0sea.h"
#include "os0file.h"
#include "page0zip.h"
#include "log0recv.h"
#include "srv0srv.h"
#include "srv0mon.h"
#include "my_cpu.h"
/** Flush this many pages in buf_LRU_get_free_block() */
size_t innodb_lru_flush_size;
/** The number of blocks from the LRU_old pointer onward, including
the block pointed to, must be buf_pool.LRU_old_ratio/BUF_LRU_OLD_RATIO_DIV
of the whole LRU list length, except that the tolerance defined below
is allowed. Note that the tolerance must be small enough such that for
even the BUF_LRU_OLD_MIN_LEN long LRU list, the LRU_old pointer is not
allowed to point to either end of the LRU list. */
static constexpr ulint BUF_LRU_OLD_TOLERANCE = 20;
/** The minimum amount of non-old blocks when the LRU_old list exists
(that is, when there are more than BUF_LRU_OLD_MIN_LEN blocks).
@see buf_LRU_old_adjust_len */
#define BUF_LRU_NON_OLD_MIN_LEN 5
/** If we switch on the InnoDB monitor because there are too few available
frames in the buffer pool, we set this to TRUE */
static bool buf_lru_switched_on_innodb_mon = false;
/** True if diagnostic message about difficult to find free blocks
in the buffer bool has already printed. */
static bool buf_lru_free_blocks_error_printed;
/******************************************************************//**
These statistics are not 'of' LRU but 'for' LRU. We keep count of I/O
and page_zip_decompress() operations. Based on the statistics,
buf_LRU_evict_from_unzip_LRU() decides if we want to evict from
unzip_LRU or the regular LRU. From unzip_LRU, we will only evict the
uncompressed frame (meaning we can evict dirty blocks as well). From
the regular LRU, we will evict the entire block (i.e.: both the
uncompressed and compressed data), which must be clean. */
/* @{ */
/** Number of intervals for which we keep the history of these stats.
Updated at SRV_MONITOR_INTERVAL (the buf_LRU_stat_update() call rate). */
static constexpr ulint BUF_LRU_STAT_N_INTERVAL= 4;
/** Co-efficient with which we multiply I/O operations to equate them
with page_zip_decompress() operations. */
static constexpr ulint BUF_LRU_IO_TO_UNZIP_FACTOR= 50;
/** Sampled values buf_LRU_stat_cur.
Not protected by any mutex. Updated by buf_LRU_stat_update(). */
static buf_LRU_stat_t buf_LRU_stat_arr[BUF_LRU_STAT_N_INTERVAL];
/** Cursor to buf_LRU_stat_arr[] that is updated in a round-robin fashion. */
static ulint buf_LRU_stat_arr_ind;
/** Current operation counters. Not protected by any mutex. Cleared
by buf_LRU_stat_update(). */
buf_LRU_stat_t buf_LRU_stat_cur;
/** Running sum of past values of buf_LRU_stat_cur.
Updated by buf_LRU_stat_update(). Not Protected by any mutex. */
buf_LRU_stat_t buf_LRU_stat_sum;
/* @} */
/** @name Heuristics for detecting index scan @{ */
/** Move blocks to "new" LRU list only if the first access was at
least this many milliseconds ago. Not protected by any mutex or latch. */
uint buf_LRU_old_threshold_ms;
/* @} */
/** Remove bpage from buf_pool.LRU and buf_pool.page_hash.
If !bpage->frame && bpage->oldest_modification() <= 1,
the object will be freed.
@param bpage buffer block
@param id page identifier
@param chain locked buf_pool.page_hash chain (will be released here)
@param zip whether bpage->zip of BUF_BLOCK_FILE_PAGE should be freed
If a compressed page is freed other compressed pages may be relocated.
@retval true if bpage with bpage->frame was removed from page_hash. The
caller needs to free the page to the free list
@retval false if block without bpage->frame was removed from page_hash. In
this case the block is already returned to the buddy allocator. */
static bool buf_LRU_block_remove_hashed(buf_page_t *bpage, const page_id_t id,
buf_pool_t::hash_chain &chain,
bool zip);
/** Free a block to buf_pool */
static void buf_LRU_block_free_hashed_page(buf_block_t *block)
{
block->page.free_file_page();
buf_LRU_block_free_non_file_page(block);
}
/** Increase LRU size in bytes by the page size.
@param[in] bpage control block */
static inline void incr_LRU_size_in_bytes(const buf_page_t* bpage)
{
/* FIXME: use atomics, not mutex */
mysql_mutex_assert_owner(&buf_pool.mutex);
buf_pool.stat.LRU_bytes += bpage->physical_size();
ut_ad(buf_pool.stat.LRU_bytes <= buf_pool.curr_pool_size);
}
/** @return whether the unzip_LRU list should be used for evicting a victim
instead of the general LRU list */
bool buf_LRU_evict_from_unzip_LRU()
{
mysql_mutex_assert_owner(&buf_pool.mutex);
/* If the unzip_LRU list is empty, we can only use the LRU. */
if (UT_LIST_GET_LEN(buf_pool.unzip_LRU) == 0) {
return false;
}
/* If unzip_LRU is at most 10% of the size of the LRU list,
then use the LRU. This slack allows us to keep hot
decompressed pages in the buffer pool. */
if (UT_LIST_GET_LEN(buf_pool.unzip_LRU)
<= UT_LIST_GET_LEN(buf_pool.LRU) / 10) {
return false;
}
/* If eviction hasn't started yet, we assume by default
that a workload is disk bound. */
if (buf_pool.freed_page_clock == 0) {
return true;
}
/* Calculate the average over past intervals, and add the values
of the current interval. */
ulint io_avg = buf_LRU_stat_sum.io / BUF_LRU_STAT_N_INTERVAL
+ buf_LRU_stat_cur.io;
ulint unzip_avg = buf_LRU_stat_sum.unzip / BUF_LRU_STAT_N_INTERVAL
+ buf_LRU_stat_cur.unzip;
/* Decide based on our formula. If the load is I/O bound
(unzip_avg is smaller than the weighted io_avg), evict an
uncompressed frame from unzip_LRU. Otherwise we assume that
the load is CPU bound and evict from the regular LRU. */
return(unzip_avg <= io_avg * BUF_LRU_IO_TO_UNZIP_FACTOR);
}
/** Try to free an uncompressed page of a compressed block from the unzip
LRU list. The compressed page is preserved, and it need not be clean.
@param limit maximum number of blocks to scan
@return true if freed */
static bool buf_LRU_free_from_unzip_LRU_list(ulint limit)
{
mysql_mutex_assert_owner(&buf_pool.mutex);
if (!buf_LRU_evict_from_unzip_LRU()) {
return(false);
}
ulint scanned = 0;
bool freed = false;
for (buf_block_t* block = UT_LIST_GET_LAST(buf_pool.unzip_LRU);
block && scanned < limit; ++scanned) {
buf_block_t* prev_block = UT_LIST_GET_PREV(unzip_LRU, block);
ut_ad(block->page.in_file());
ut_ad(block->page.belongs_to_unzip_LRU());
ut_ad(block->in_unzip_LRU_list);
ut_ad(block->page.in_LRU_list);
freed = buf_LRU_free_page(&block->page, false);
if (freed) {
break;
}
block = prev_block;
}
if (scanned) {
MONITOR_INC_VALUE_CUMULATIVE(
MONITOR_LRU_UNZIP_SEARCH_SCANNED,
MONITOR_LRU_UNZIP_SEARCH_SCANNED_NUM_CALL,
MONITOR_LRU_UNZIP_SEARCH_SCANNED_PER_CALL,
scanned);
}
return(freed);
}
/** Try to free a clean page from the common LRU list.
@param limit maximum number of blocks to scan
@return whether a page was freed */
static bool buf_LRU_free_from_common_LRU_list(ulint limit)
{
mysql_mutex_assert_owner(&buf_pool.mutex);
ulint scanned = 0;
bool freed = false;
for (buf_page_t* bpage = buf_pool.lru_scan_itr.start();
bpage && scanned < limit;
++scanned, bpage = buf_pool.lru_scan_itr.get()) {
buf_page_t* prev = UT_LIST_GET_PREV(LRU, bpage);
buf_pool.lru_scan_itr.set(prev);
const auto accessed = bpage->is_accessed();
if (buf_LRU_free_page(bpage, true)) {
if (!accessed) {
/* Keep track of pages that are evicted without
ever being accessed. This gives us a measure of
the effectiveness of readahead */
++buf_pool.stat.n_ra_pages_evicted;
}
freed = true;
break;
}
}
if (scanned) {
MONITOR_INC_VALUE_CUMULATIVE(
MONITOR_LRU_SEARCH_SCANNED,
MONITOR_LRU_SEARCH_SCANNED_NUM_CALL,
MONITOR_LRU_SEARCH_SCANNED_PER_CALL,
scanned);
}
return(freed);
}
/** @return a buffer block from the buf_pool.free list
@retval NULL if the free list is empty */
buf_block_t* buf_LRU_get_free_only()
{
buf_block_t* block;
mysql_mutex_assert_owner(&buf_pool.mutex);
block = reinterpret_cast<buf_block_t*>(
UT_LIST_GET_FIRST(buf_pool.free));
while (block != NULL) {
ut_ad(block->page.in_free_list);
ut_d(block->page.in_free_list = FALSE);
ut_ad(!block->page.oldest_modification());
ut_ad(!block->page.in_LRU_list);
ut_a(!block->page.in_file());
UT_LIST_REMOVE(buf_pool.free, &block->page);
if (buf_pool.curr_size >= buf_pool.old_size
|| UT_LIST_GET_LEN(buf_pool.withdraw)
>= buf_pool.withdraw_target
|| !buf_pool.will_be_withdrawn(block->page)) {
/* No adaptive hash index entries may point to
a free block. */
assert_block_ahi_empty(block);
block->page.set_state(buf_page_t::MEMORY);
MEM_MAKE_ADDRESSABLE(block->page.frame, srv_page_size);
break;
}
/* This should be withdrawn */
UT_LIST_ADD_LAST(buf_pool.withdraw, &block->page);
ut_d(block->in_withdraw_list = true);
block = reinterpret_cast<buf_block_t*>(
UT_LIST_GET_FIRST(buf_pool.free));
}
return(block);
}
/******************************************************************//**
Checks how much of buf_pool is occupied by non-data objects like
AHI, lock heaps etc. Depending on the size of non-data objects this
function will either assert or issue a warning and switch on the
status monitor. */
static void buf_LRU_check_size_of_non_data_objects()
{
mysql_mutex_assert_owner(&buf_pool.mutex);
if (recv_recovery_is_on() || buf_pool.curr_size != buf_pool.old_size)
return;
const auto s= UT_LIST_GET_LEN(buf_pool.free) + UT_LIST_GET_LEN(buf_pool.LRU);
if (s < buf_pool.curr_size / 20)
ib::fatal() << "Over 95 percent of the buffer pool is"
" occupied by lock heaps"
#ifdef BTR_CUR_HASH_ADAPT
" or the adaptive hash index"
#endif /* BTR_CUR_HASH_ADAPT */
"! Check that your transactions do not set too many"
" row locks, or review if innodb_buffer_pool_size="
<< (buf_pool.curr_size >> (20U - srv_page_size_shift))
<< "M could be bigger.";
if (s < buf_pool.curr_size / 3)
{
if (!buf_lru_switched_on_innodb_mon && srv_monitor_timer)
{
/* Over 67 % of the buffer pool is occupied by lock heaps or
the adaptive hash index. This may be a memory leak! */
ib::warn() << "Over 67 percent of the buffer pool is"
" occupied by lock heaps"
#ifdef BTR_CUR_HASH_ADAPT
" or the adaptive hash index"
#endif /* BTR_CUR_HASH_ADAPT */
"! Check that your transactions do not set too many row locks."
" innodb_buffer_pool_size="
<< (buf_pool.curr_size >> (20U - srv_page_size_shift))
<< "M. Starting the InnoDB Monitor to print diagnostics.";
buf_lru_switched_on_innodb_mon= true;
srv_print_innodb_monitor= TRUE;
srv_monitor_timer_schedule_now();
}
}
else if (buf_lru_switched_on_innodb_mon)
{
/* Switch off the InnoDB Monitor; this is a simple way to stop the
monitor if the situation becomes less urgent, but may also
surprise users who did SET GLOBAL innodb_status_output=ON earlier! */
buf_lru_switched_on_innodb_mon= false;
srv_print_innodb_monitor= FALSE;
}
}
/** Get a block from the buf_pool.free list.
If the list is empty, blocks will be moved from the end of buf_pool.LRU
to buf_pool.free.
This function is called from a user thread when it needs a clean
block to read in a page. Note that we only ever get a block from
the free list. Even when we flush a page or find a page in LRU scan
we put it to free list to be used.
* iteration 0:
* get a block from the buf_pool.free list, success:done
* if buf_pool.try_LRU_scan is set
* scan LRU up to 100 pages to free a clean block
* success:retry the free list
* flush up to innodb_lru_flush_size LRU blocks to data files
(until UT_LIST_GET_GEN(buf_pool.free) < innodb_lru_scan_depth)
* on buf_page_write_complete() the blocks will put on buf_pool.free list
* success: retry the free list
* subsequent iterations: same as iteration 0 except:
* scan whole LRU list
* scan LRU list even if buf_pool.try_LRU_scan is not set
@param have_mutex whether buf_pool.mutex is already being held
@return the free control block, in state BUF_BLOCK_MEMORY */
buf_block_t *buf_LRU_get_free_block(bool have_mutex)
{
ulint n_iterations = 0;
ulint flush_failures = 0;
MONITOR_INC(MONITOR_LRU_GET_FREE_SEARCH);
if (have_mutex) {
mysql_mutex_assert_owner(&buf_pool.mutex);
goto got_mutex;
}
mysql_mutex_lock(&buf_pool.mutex);
got_mutex:
buf_LRU_check_size_of_non_data_objects();
buf_block_t* block;
DBUG_EXECUTE_IF("ib_lru_force_no_free_page",
if (!buf_lru_free_blocks_error_printed) {
n_iterations = 21;
goto not_found;});
retry:
/* If there is a block in the free list, take it */
if ((block = buf_LRU_get_free_only()) != nullptr) {
got_block:
if (!have_mutex) {
mysql_mutex_unlock(&buf_pool.mutex);
}
block->page.zip.clear();
return block;
}
MONITOR_INC( MONITOR_LRU_GET_FREE_LOOPS );
if (n_iterations || buf_pool.try_LRU_scan) {
/* If no block was in the free list, search from the
end of the LRU list and try to free a block there.
If we are doing for the first time we'll scan only
tail of the LRU list otherwise we scan the whole LRU
list. */
if (buf_LRU_scan_and_free_block(n_iterations
? ULINT_UNDEFINED : 100)) {
goto retry;
}
/* Tell other threads that there is no point
in scanning the LRU list. */
buf_pool.try_LRU_scan = false;
}
for (;;) {
if ((block = buf_LRU_get_free_only()) != nullptr) {
goto got_block;
}
if (!buf_pool.n_flush_LRU_) {
break;
}
my_cond_wait(&buf_pool.done_free, &buf_pool.mutex.m_mutex);
}
#ifndef DBUG_OFF
not_found:
#endif
mysql_mutex_unlock(&buf_pool.mutex);
if (n_iterations > 20 && !buf_lru_free_blocks_error_printed
&& srv_buf_pool_old_size == srv_buf_pool_size) {
ib::warn() << "Difficult to find free blocks in the buffer pool"
" (" << n_iterations << " search iterations)! "
<< flush_failures << " failed attempts to"
" flush a page!"
" Consider increasing innodb_buffer_pool_size."
" Pending flushes (fsync): "
<< fil_n_pending_tablespace_flushes
<< ". " << os_n_file_reads << " OS file reads, "
<< os_n_file_writes << " OS file writes, "
<< os_n_fsyncs
<< " OS fsyncs.";
buf_lru_free_blocks_error_printed = true;
}
if (n_iterations > 1) {
MONITOR_INC( MONITOR_LRU_GET_FREE_WAITS );
}
/* No free block was found: try to flush the LRU list.
The freed blocks will be up for grabs for all threads.
TODO: A more elegant way would have been to return one freed
up block to the caller here but the code that deals with
removing the block from buf_pool.page_hash and buf_pool.LRU is fairly
involved (particularly in case of ROW_FORMAT=COMPRESSED pages). We
can do that in a separate patch sometime in future. */
if (!buf_flush_LRU(innodb_lru_flush_size)) {
MONITOR_INC(MONITOR_LRU_SINGLE_FLUSH_FAILURE_COUNT);
++flush_failures;
}
n_iterations++;
mysql_mutex_lock(&buf_pool.mutex);
buf_pool.stat.LRU_waits++;
goto got_mutex;
}
/** Move the LRU_old pointer so that the length of the old blocks list
is inside the allowed limits. */
static void buf_LRU_old_adjust_len()
{
ulint old_len;
ulint new_len;
ut_a(buf_pool.LRU_old);
mysql_mutex_assert_owner(&buf_pool.mutex);
ut_ad(buf_pool.LRU_old_ratio >= BUF_LRU_OLD_RATIO_MIN);
ut_ad(buf_pool.LRU_old_ratio <= BUF_LRU_OLD_RATIO_MAX);
compile_time_assert(BUF_LRU_OLD_RATIO_MIN * BUF_LRU_OLD_MIN_LEN
> BUF_LRU_OLD_RATIO_DIV
* (BUF_LRU_OLD_TOLERANCE + 5));
compile_time_assert(BUF_LRU_NON_OLD_MIN_LEN < BUF_LRU_OLD_MIN_LEN);
#ifdef UNIV_LRU_DEBUG
/* buf_pool.LRU_old must be the first item in the LRU list
whose "old" flag is set. */
ut_a(buf_pool.LRU_old->old);
ut_a(!UT_LIST_GET_PREV(LRU, buf_pool.LRU_old)
|| !UT_LIST_GET_PREV(LRU, buf_pool.LRU_old)->old);
ut_a(!UT_LIST_GET_NEXT(LRU, buf_pool.LRU_old)
|| UT_LIST_GET_NEXT(LRU, buf_pool.LRU_old)->old);
#endif /* UNIV_LRU_DEBUG */
old_len = buf_pool.LRU_old_len;
new_len = ut_min(UT_LIST_GET_LEN(buf_pool.LRU)
* buf_pool.LRU_old_ratio / BUF_LRU_OLD_RATIO_DIV,
UT_LIST_GET_LEN(buf_pool.LRU)
- (BUF_LRU_OLD_TOLERANCE
+ BUF_LRU_NON_OLD_MIN_LEN));
for (;;) {
buf_page_t* LRU_old = buf_pool.LRU_old;
ut_a(LRU_old);
ut_ad(LRU_old->in_LRU_list);
#ifdef UNIV_LRU_DEBUG
ut_a(LRU_old->old);
#endif /* UNIV_LRU_DEBUG */
/* Update the LRU_old pointer if necessary */
if (old_len + BUF_LRU_OLD_TOLERANCE < new_len) {
buf_pool.LRU_old = LRU_old = UT_LIST_GET_PREV(
LRU, LRU_old);
#ifdef UNIV_LRU_DEBUG
ut_a(!LRU_old->old);
#endif /* UNIV_LRU_DEBUG */
old_len = ++buf_pool.LRU_old_len;
LRU_old->set_old(true);
} else if (old_len > new_len + BUF_LRU_OLD_TOLERANCE) {
buf_pool.LRU_old = UT_LIST_GET_NEXT(LRU, LRU_old);
old_len = --buf_pool.LRU_old_len;
LRU_old->set_old(false);
} else {
return;
}
}
}
/** Initialize the old blocks pointer in the LRU list. This function should be
called when the LRU list grows to BUF_LRU_OLD_MIN_LEN length. */
static void buf_LRU_old_init()
{
mysql_mutex_assert_owner(&buf_pool.mutex);
ut_a(UT_LIST_GET_LEN(buf_pool.LRU) == BUF_LRU_OLD_MIN_LEN);
/* We first initialize all blocks in the LRU list as old and then use
the adjust function to move the LRU_old pointer to the right
position */
for (buf_page_t* bpage = UT_LIST_GET_LAST(buf_pool.LRU);
bpage != NULL;
bpage = UT_LIST_GET_PREV(LRU, bpage)) {
ut_ad(bpage->in_LRU_list);
/* This loop temporarily violates the
assertions of buf_page_t::set_old(). */
bpage->old = true;
}
buf_pool.LRU_old = UT_LIST_GET_FIRST(buf_pool.LRU);
buf_pool.LRU_old_len = UT_LIST_GET_LEN(buf_pool.LRU);
buf_LRU_old_adjust_len();
}
/** Remove a block from the unzip_LRU list if it belonged to the list.
@param[in] bpage control block */
static void buf_unzip_LRU_remove_block_if_needed(buf_page_t* bpage)
{
ut_ad(bpage->in_file());
mysql_mutex_assert_owner(&buf_pool.mutex);
if (bpage->belongs_to_unzip_LRU()) {
buf_block_t* block = reinterpret_cast<buf_block_t*>(bpage);
ut_ad(block->in_unzip_LRU_list);
ut_d(block->in_unzip_LRU_list = false);
UT_LIST_REMOVE(buf_pool.unzip_LRU, block);
}
}
/** Removes a block from the LRU list.
@param[in] bpage control block */
static inline void buf_LRU_remove_block(buf_page_t* bpage)
{
/* Important that we adjust the hazard pointers before removing
bpage from the LRU list. */
buf_page_t* prev_bpage = buf_pool.LRU_remove(bpage);
/* If the LRU_old pointer is defined and points to just this block,
move it backward one step */
if (bpage == buf_pool.LRU_old) {
/* Below: the previous block is guaranteed to exist,
because the LRU_old pointer is only allowed to differ
by BUF_LRU_OLD_TOLERANCE from strict
buf_pool.LRU_old_ratio/BUF_LRU_OLD_RATIO_DIV of the LRU
list length. */
ut_a(prev_bpage);
#ifdef UNIV_LRU_DEBUG
ut_a(!prev_bpage->old);
#endif /* UNIV_LRU_DEBUG */
buf_pool.LRU_old = prev_bpage;
prev_bpage->set_old(true);
buf_pool.LRU_old_len++;
}
buf_pool.stat.LRU_bytes -= bpage->physical_size();
buf_unzip_LRU_remove_block_if_needed(bpage);
/* If the LRU list is so short that LRU_old is not defined,
clear the "old" flags and return */
if (UT_LIST_GET_LEN(buf_pool.LRU) < BUF_LRU_OLD_MIN_LEN) {
for (buf_page_t* bpage = UT_LIST_GET_FIRST(buf_pool.LRU);
bpage != NULL;
bpage = UT_LIST_GET_NEXT(LRU, bpage)) {
/* This loop temporarily violates the
assertions of buf_page_t::set_old(). */
bpage->old = false;
}
buf_pool.LRU_old = NULL;
buf_pool.LRU_old_len = 0;
return;
}
ut_ad(buf_pool.LRU_old);
/* Update the LRU_old_len field if necessary */
if (bpage->old) {
buf_pool.LRU_old_len--;
}
/* Adjust the length of the old block list if necessary */
buf_LRU_old_adjust_len();
}
/******************************************************************//**
Adds a block to the LRU list of decompressed zip pages. */
void
buf_unzip_LRU_add_block(
/*====================*/
buf_block_t* block, /*!< in: control block */
ibool old) /*!< in: TRUE if should be put to the end
of the list, else put to the start */
{
mysql_mutex_assert_owner(&buf_pool.mutex);
ut_a(block->page.belongs_to_unzip_LRU());
ut_ad(!block->in_unzip_LRU_list);
ut_d(block->in_unzip_LRU_list = true);
if (old) {
UT_LIST_ADD_LAST(buf_pool.unzip_LRU, block);
} else {
UT_LIST_ADD_FIRST(buf_pool.unzip_LRU, block);
}
}
/******************************************************************//**
Adds a block to the LRU list. Please make sure that the page_size is
already set when invoking the function, so that we can get correct
page_size from the buffer page when adding a block into LRU */
void
buf_LRU_add_block(
buf_page_t* bpage, /*!< in: control block */
bool old) /*!< in: true if should be put to the old blocks
in the LRU list, else put to the start; if the
LRU list is very short, the block is added to
the start, regardless of this parameter */
{
mysql_mutex_assert_owner(&buf_pool.mutex);
ut_ad(!bpage->in_LRU_list);
if (!old || (UT_LIST_GET_LEN(buf_pool.LRU) < BUF_LRU_OLD_MIN_LEN)) {
UT_LIST_ADD_FIRST(buf_pool.LRU, bpage);
bpage->freed_page_clock = buf_pool.freed_page_clock
& ((1U << 31) - 1);
} else {
#ifdef UNIV_LRU_DEBUG
/* buf_pool.LRU_old must be the first item in the LRU list
whose "old" flag is set. */
ut_a(buf_pool.LRU_old->old);
ut_a(!UT_LIST_GET_PREV(LRU, buf_pool.LRU_old)
|| !UT_LIST_GET_PREV(LRU, buf_pool.LRU_old)->old);
ut_a(!UT_LIST_GET_NEXT(LRU, buf_pool.LRU_old)
|| UT_LIST_GET_NEXT(LRU, buf_pool.LRU_old)->old);
#endif /* UNIV_LRU_DEBUG */
UT_LIST_INSERT_AFTER(buf_pool.LRU, buf_pool.LRU_old,
bpage);
buf_pool.LRU_old_len++;
}
ut_d(bpage->in_LRU_list = TRUE);
incr_LRU_size_in_bytes(bpage);
if (UT_LIST_GET_LEN(buf_pool.LRU) > BUF_LRU_OLD_MIN_LEN) {
ut_ad(buf_pool.LRU_old);
/* Adjust the length of the old block list if necessary */
bpage->set_old(old);
buf_LRU_old_adjust_len();
} else if (UT_LIST_GET_LEN(buf_pool.LRU) == BUF_LRU_OLD_MIN_LEN) {
/* The LRU list is now long enough for LRU_old to become
defined: init it */
buf_LRU_old_init();
} else {
bpage->set_old(buf_pool.LRU_old != NULL);
}
/* If this is a zipped block with decompressed frame as well
then put it on the unzip_LRU list */
if (bpage->belongs_to_unzip_LRU()) {
buf_unzip_LRU_add_block((buf_block_t*) bpage, old);
}
}
/** Move a block to the start of the LRU list. */
void buf_page_make_young(buf_page_t *bpage)
{
if (bpage->is_read_fixed())
return;
ut_ad(bpage->in_file());
mysql_mutex_lock(&buf_pool.mutex);
if (UNIV_UNLIKELY(bpage->old))
buf_pool.stat.n_pages_made_young++;
buf_LRU_remove_block(bpage);
buf_LRU_add_block(bpage, false);
mysql_mutex_unlock(&buf_pool.mutex);
}
/** Try to free a block. If bpage is a descriptor of a compressed-only
ROW_FORMAT=COMPRESSED page, the buf_page_t object will be freed as well.
The caller must hold buf_pool.mutex.
@param bpage block to be freed
@param zip whether to remove both copies of a ROW_FORMAT=COMPRESSED page
@retval true if freed and buf_pool.mutex may have been temporarily released
@retval false if the page was not freed */
bool buf_LRU_free_page(buf_page_t *bpage, bool zip)
{
const page_id_t id{bpage->id()};
buf_page_t* b = nullptr;
mysql_mutex_assert_owner(&buf_pool.mutex);
/* First, perform a quick check before we acquire hash_lock. */
if (!bpage->can_relocate()) {
return false;
}
/* We must hold an exclusive hash_lock to prevent
bpage->can_relocate() from changing due to a concurrent
execution of buf_page_get_low(). */
buf_pool_t::hash_chain& chain= buf_pool.page_hash.cell_get(id.fold());
page_hash_latch& hash_lock = buf_pool.page_hash.lock_get(chain);
/* We cannot use transactional_lock_guard here,
because buf_buddy_relocate() in buf_buddy_free() could get stuck. */
hash_lock.lock();
lsn_t oldest_modification = bpage->oldest_modification_acquire();
if (UNIV_UNLIKELY(!bpage->can_relocate())) {
/* Do not free buffer fixed and I/O-fixed blocks. */
goto func_exit;
}
if (oldest_modification == 1) {
mysql_mutex_lock(&buf_pool.flush_list_mutex);
oldest_modification = bpage->oldest_modification();
if (oldest_modification) {
ut_ad(oldest_modification == 1);
buf_pool.delete_from_flush_list(bpage);
}
mysql_mutex_unlock(&buf_pool.flush_list_mutex);
ut_ad(!bpage->oldest_modification());
oldest_modification = 0;
}
if (zip || !bpage->zip.data) {
/* This would completely free the block. */
/* Do not completely free dirty blocks. */
if (oldest_modification) {
goto func_exit;
}
} else if (oldest_modification && !bpage->frame) {
func_exit:
hash_lock.unlock();
return(false);
} else if (bpage->frame) {
b = static_cast<buf_page_t*>(ut_zalloc_nokey(sizeof *b));
ut_a(b);
mysql_mutex_lock(&buf_pool.flush_list_mutex);
new (b) buf_page_t(*bpage);
b->frame = nullptr;
b->set_state(buf_page_t::UNFIXED + 1);
}
mysql_mutex_assert_owner(&buf_pool.mutex);
DBUG_PRINT("ib_buf", ("free page %u:%u",
id.space(), id.page_no()));
ut_ad(bpage->can_relocate());
if (!buf_LRU_block_remove_hashed(bpage, id, chain, zip)) {
ut_ad(!b);
mysql_mutex_assert_not_owner(&buf_pool.flush_list_mutex);
return(true);
}
/* We have just freed a BUF_BLOCK_FILE_PAGE. If b != nullptr
then it was a compressed page with an uncompressed frame and
we are interested in freeing only the uncompressed frame.
Therefore we have to reinsert the compressed page descriptor
into the LRU and page_hash (and possibly flush_list).
if !b then it was a regular page that has been freed */
if (UNIV_LIKELY_NULL(b)) {
buf_page_t* prev_b = UT_LIST_GET_PREV(LRU, b);
ut_ad(!buf_pool.page_hash.get(id, chain));
ut_ad(b->zip_size());
/* The field in_LRU_list of
the to-be-freed block descriptor should have
been cleared in
buf_LRU_block_remove_hashed(), which
invokes buf_LRU_remove_block(). */
ut_ad(!bpage->in_LRU_list);
ut_ad(bpage->frame);
ut_ad(!((buf_block_t*) bpage)->in_unzip_LRU_list);
/* The fields of bpage were copied to b before
buf_LRU_block_remove_hashed() was invoked. */
ut_ad(!b->in_zip_hash);
ut_ad(b->in_LRU_list);
ut_ad(b->in_page_hash);
ut_d(b->in_page_hash = false);
b->hash = nullptr;
buf_pool.page_hash.append(chain, b);
/* Insert b where bpage was in the LRU list. */
if (prev_b) {
ulint lru_len;
ut_ad(prev_b->in_LRU_list);
ut_ad(prev_b->in_file());
UT_LIST_INSERT_AFTER(buf_pool.LRU, prev_b, b);
incr_LRU_size_in_bytes(b);
if (b->is_old()) {
buf_pool.LRU_old_len++;
if (buf_pool.LRU_old
== UT_LIST_GET_NEXT(LRU, b)) {
buf_pool.LRU_old = b;
}
}
lru_len = UT_LIST_GET_LEN(buf_pool.LRU);
if (lru_len > BUF_LRU_OLD_MIN_LEN) {
ut_ad(buf_pool.LRU_old);
/* Adjust the length of the
old block list if necessary */
buf_LRU_old_adjust_len();
} else if (lru_len == BUF_LRU_OLD_MIN_LEN) {
/* The LRU list is now long
enough for LRU_old to become
defined: init it */
buf_LRU_old_init();
}
#ifdef UNIV_LRU_DEBUG
/* Check that the "old" flag is consistent
in the block and its neighbours. */
b->set_old(b->is_old());
#endif /* UNIV_LRU_DEBUG */
} else {
ut_d(b->in_LRU_list = FALSE);
buf_LRU_add_block(b, b->old);
}
buf_flush_relocate_on_flush_list(bpage, b);
mysql_mutex_unlock(&buf_pool.flush_list_mutex);
bpage->zip.data = nullptr;
page_zip_set_size(&bpage->zip, 0);
b->lock.x_lock();
hash_lock.unlock();
} else if (!zip) {
hash_lock.unlock();
}
buf_block_t* block = reinterpret_cast<buf_block_t*>(bpage);
#ifdef BTR_CUR_HASH_ADAPT
if (block->index) {
mysql_mutex_unlock(&buf_pool.mutex);
/* Remove the adaptive hash index on the page.
The page was declared uninitialized by
buf_LRU_block_remove_hashed(). We need to flag
the contents of the page valid (which it still is) in
order to avoid bogus Valgrind or MSAN warnings.*/
MEM_MAKE_DEFINED(block->page.frame, srv_page_size);
btr_search_drop_page_hash_index(block);
MEM_UNDEFINED(block->page.frame, srv_page_size);
mysql_mutex_lock(&buf_pool.mutex);
}
#endif
if (UNIV_LIKELY_NULL(b)) {
ut_ad(b->zip_size());
b->lock.x_unlock();
b->unfix();
}
buf_LRU_block_free_hashed_page(block);
return(true);
}
/******************************************************************//**
Puts a block back to the free list. */
void
buf_LRU_block_free_non_file_page(
/*=============================*/
buf_block_t* block) /*!< in: block, must not contain a file page */
{
void* data;
ut_ad(block->page.state() == buf_page_t::MEMORY);
assert_block_ahi_empty(block);
ut_ad(!block->page.in_free_list);
ut_ad(!block->page.oldest_modification());
ut_ad(!block->page.in_LRU_list);
ut_ad(!block->page.hash);
block->page.set_state(buf_page_t::NOT_USED);
MEM_UNDEFINED(block->page.frame, srv_page_size);
/* Wipe page_no and space_id */
static_assert(FIL_PAGE_OFFSET % 4 == 0, "alignment");
memset_aligned<4>(block->page.frame + FIL_PAGE_OFFSET, 0xfe, 4);
static_assert(FIL_PAGE_ARCH_LOG_NO_OR_SPACE_ID % 4 == 2,
"not perfect alignment");
memset_aligned<2>(block->page.frame + FIL_PAGE_ARCH_LOG_NO_OR_SPACE_ID,
0xfe, 4);
data = block->page.zip.data;
if (data != NULL) {
block->page.zip.data = NULL;
buf_pool_mutex_exit_forbid();
ut_ad(block->zip_size());
buf_buddy_free(data, block->zip_size());
buf_pool_mutex_exit_allow();
page_zip_set_size(&block->page.zip, 0);
}
if (buf_pool.curr_size < buf_pool.old_size
&& UT_LIST_GET_LEN(buf_pool.withdraw) < buf_pool.withdraw_target
&& buf_pool.will_be_withdrawn(block->page)) {
/* This should be withdrawn */
UT_LIST_ADD_LAST(
buf_pool.withdraw,
&block->page);
ut_d(block->in_withdraw_list = true);
} else {
UT_LIST_ADD_FIRST(buf_pool.free, &block->page);
ut_d(block->page.in_free_list = true);
pthread_cond_signal(&buf_pool.done_free);
}
MEM_NOACCESS(block->page.frame, srv_page_size);
}
/** Release a memory block to the buffer pool. */
ATTRIBUTE_COLD void buf_pool_t::free_block(buf_block_t *block)
{
ut_ad(this == &buf_pool);
mysql_mutex_lock(&mutex);
buf_LRU_block_free_non_file_page(block);
mysql_mutex_unlock(&mutex);
}
/** Remove bpage from buf_pool.LRU and buf_pool.page_hash.
If !bpage->frame && !bpage->oldest_modification(), the object will be freed.
@param bpage buffer block
@param id page identifier
@param chain locked buf_pool.page_hash chain (will be released here)
@param zip whether bpage->zip of BUF_BLOCK_FILE_PAGE should be freed
If a compressed page is freed other compressed pages may be relocated.
@retval true if BUF_BLOCK_FILE_PAGE was removed from page_hash. The
caller needs to free the page to the free list
@retval false if BUF_BLOCK_ZIP_PAGE was removed from page_hash. In
this case the block is already returned to the buddy allocator. */
static bool buf_LRU_block_remove_hashed(buf_page_t *bpage, const page_id_t id,
buf_pool_t::hash_chain &chain,
bool zip)
{
ut_a(bpage->can_relocate());
ut_ad(buf_pool.page_hash.lock_get(chain).is_write_locked());
buf_LRU_remove_block(bpage);
buf_pool.freed_page_clock += 1;
if (UNIV_LIKELY(bpage->frame != nullptr)) {
MEM_CHECK_ADDRESSABLE(bpage, sizeof(buf_block_t));
MEM_CHECK_ADDRESSABLE(bpage->frame, srv_page_size);
buf_block_modify_clock_inc((buf_block_t*) bpage);
if (UNIV_LIKELY_NULL(bpage->zip.data)) {
const page_t* page = bpage->frame;
ut_a(!zip || !bpage->oldest_modification());
ut_ad(bpage->zip_size());
switch (fil_page_get_type(page)) {
case FIL_PAGE_TYPE_ALLOCATED:
case FIL_PAGE_INODE:
case FIL_PAGE_IBUF_BITMAP:
case FIL_PAGE_TYPE_FSP_HDR:
case FIL_PAGE_TYPE_XDES:
/* These are essentially uncompressed pages. */
if (!zip) {
/* InnoDB writes the data to the
uncompressed page frame. Copy it
to the compressed page, which will
be preserved. */
memcpy(bpage->zip.data, page,
bpage->zip_size());
}
break;
case FIL_PAGE_TYPE_ZBLOB:
case FIL_PAGE_TYPE_ZBLOB2:
break;
case FIL_PAGE_INDEX:
case FIL_PAGE_RTREE:
#if defined UNIV_ZIP_DEBUG && defined BTR_CUR_HASH_ADAPT
/* During recovery, we only update the
compressed page, not the uncompressed one. */
ut_a(recv_recovery_is_on()
|| page_zip_validate(
&bpage->zip, page,
((buf_block_t*) bpage)->index));
#endif /* UNIV_ZIP_DEBUG && BTR_CUR_HASH_ADAPT */
break;
default:
ib::error() << "The compressed page to be"
" evicted seems corrupt:";
ut_print_buf(stderr, page, srv_page_size);
ib::error() << "Possibly older version of"
" the page:";
ut_print_buf(stderr, bpage->zip.data,
bpage->zip_size());
putc('\n', stderr);
ut_error;
}
} else {
goto evict_zip;
}
} else {
evict_zip:
ut_a(!bpage->oldest_modification());
MEM_CHECK_ADDRESSABLE(bpage->zip.data, bpage->zip_size());
}
ut_ad(!bpage->in_zip_hash);
buf_pool.page_hash.remove(chain, bpage);
page_hash_latch& hash_lock = buf_pool.page_hash.lock_get(chain);
if (UNIV_UNLIKELY(!bpage->frame)) {
ut_ad(!bpage->in_free_list);
ut_ad(!bpage->in_LRU_list);
ut_a(bpage->zip.data);
ut_a(bpage->zip.ssize);
ut_ad(!bpage->oldest_modification());
hash_lock.unlock();
buf_pool_mutex_exit_forbid();
buf_buddy_free(bpage->zip.data, bpage->zip_size());
buf_pool_mutex_exit_allow();
bpage->lock.free();
ut_free(bpage);
return false;
} else {
static_assert(FIL_NULL == 0xffffffffU, "fill pattern");
static_assert(FIL_PAGE_OFFSET % 4 == 0, "alignment");
memset_aligned<4>(bpage->frame + FIL_PAGE_OFFSET, 0xff, 4);
static_assert(FIL_PAGE_ARCH_LOG_NO_OR_SPACE_ID % 4 == 2,
"not perfect alignment");
memset_aligned<2>(bpage->frame
+ FIL_PAGE_ARCH_LOG_NO_OR_SPACE_ID, 0xff, 4);
MEM_UNDEFINED(bpage->frame, srv_page_size);
bpage->set_state(buf_page_t::REMOVE_HASH);
if (!zip) {
return true;
}
/* Question: If we release hash_lock here
then what protects us against:
1) Some other thread buffer fixing this page
2) Some other thread trying to read this page and
not finding it in buffer pool attempting to read it
from the disk.
Answer:
1) Cannot happen because the page is no longer in the
page_hash. Only possibility is when while invalidating
a tablespace we buffer fix the prev_page in LRU to
avoid relocation during the scan. But that is not
possible because we are holding buf_pool mutex.
2) Not possible because in buf_page_init_for_read()
we do a look up of page_hash while holding buf_pool
mutex and since we are holding buf_pool mutex here
and by the time we'll release it in the caller we'd
have inserted the compressed only descriptor in the
page_hash. */
hash_lock.unlock();
if (bpage->zip.data) {
/* Free the compressed page. */
void* data = bpage->zip.data;
bpage->zip.data = NULL;
ut_ad(!bpage->in_free_list);
ut_ad(!bpage->oldest_modification());
ut_ad(!bpage->in_LRU_list);
buf_pool_mutex_exit_forbid();
buf_buddy_free(data, bpage->zip_size());
buf_pool_mutex_exit_allow();
page_zip_set_size(&bpage->zip, 0);
}
return true;
}
}
/** Release and evict a corrupted page.
@param bpage page that was being read */
ATTRIBUTE_COLD void buf_pool_t::corrupted_evict(buf_page_t *bpage)
{
const page_id_t id{bpage->id()};
buf_pool_t::hash_chain &chain= buf_pool.page_hash.cell_get(id.fold());
page_hash_latch &hash_lock= buf_pool.page_hash.lock_get(chain);
mysql_mutex_lock(&mutex);
hash_lock.lock();
ut_ad(!bpage->oldest_modification());
bpage->set_corrupt_id();
constexpr auto read_unfix= buf_page_t::READ_FIX - buf_page_t::UNFIXED;
auto s= bpage->zip.fix.fetch_sub(read_unfix) - read_unfix;
bpage->lock.x_unlock(true);
while (s != buf_page_t::UNFIXED)
{
ut_ad(s > buf_page_t::UNFIXED);
ut_ad(s < buf_page_t::READ_FIX);
/* Wait for other threads to release the fix count
before releasing the bpage from LRU list. */
(void) LF_BACKOFF();
s= bpage->state();
}
/* remove from LRU and page_hash */
if (buf_LRU_block_remove_hashed(bpage, id, chain, true))
buf_LRU_block_free_hashed_page(reinterpret_cast<buf_block_t*>(bpage));
mysql_mutex_unlock(&mutex);
ut_d(auto n=) n_pend_reads--;
ut_ad(n > 0);
}
/** Update buf_pool.LRU_old_ratio.
@param[in] old_pct Reserve this percentage of
the buffer pool for "old" blocks
@param[in] adjust true=adjust the LRU list;
false=just assign buf_pool.LRU_old_ratio
during the initialization of InnoDB
@return updated old_pct */
uint buf_LRU_old_ratio_update(uint old_pct, bool adjust)
{
uint ratio = old_pct * BUF_LRU_OLD_RATIO_DIV / 100;
if (ratio < BUF_LRU_OLD_RATIO_MIN) {
ratio = BUF_LRU_OLD_RATIO_MIN;
} else if (ratio > BUF_LRU_OLD_RATIO_MAX) {
ratio = BUF_LRU_OLD_RATIO_MAX;
}
if (adjust) {
mysql_mutex_lock(&buf_pool.mutex);
if (ratio != buf_pool.LRU_old_ratio) {
buf_pool.LRU_old_ratio = ratio;
if (UT_LIST_GET_LEN(buf_pool.LRU)
>= BUF_LRU_OLD_MIN_LEN) {
buf_LRU_old_adjust_len();
}
}
mysql_mutex_unlock(&buf_pool.mutex);
} else {
buf_pool.LRU_old_ratio = ratio;
}
/* the reverse of
ratio = old_pct * BUF_LRU_OLD_RATIO_DIV / 100 */
return((uint) (ratio * 100 / (double) BUF_LRU_OLD_RATIO_DIV + 0.5));
}
/********************************************************************//**
Update the historical stats that we are collecting for LRU eviction
policy at the end of each interval. */
void
buf_LRU_stat_update()
{
buf_LRU_stat_t* item;
buf_LRU_stat_t cur_stat;
if (!buf_pool.freed_page_clock) {
goto func_exit;
}
/* Update the index. */
item = &buf_LRU_stat_arr[buf_LRU_stat_arr_ind];
buf_LRU_stat_arr_ind++;
buf_LRU_stat_arr_ind %= BUF_LRU_STAT_N_INTERVAL;
/* Add the current value and subtract the obsolete entry.
Since buf_LRU_stat_cur is not protected by any mutex,
it can be changing between adding to buf_LRU_stat_sum
and copying to item. Assign it to local variables to make
sure the same value assign to the buf_LRU_stat_sum
and item */
cur_stat = buf_LRU_stat_cur;
buf_LRU_stat_sum.io += cur_stat.io - item->io;
buf_LRU_stat_sum.unzip += cur_stat.unzip - item->unzip;
/* Put current entry in the array. */
memcpy(item, &cur_stat, sizeof *item);
func_exit:
/* Clear the current entry. */
memset(&buf_LRU_stat_cur, 0, sizeof buf_LRU_stat_cur);
}
#if defined __aarch64__&&defined __GNUC__&&__GNUC__==4&&!defined __clang__
/* Avoid GCC 4.8.5 internal compiler error "could not split insn".
We would only need this for buf_LRU_scan_and_free_block(),
but GCC 4.8.5 does not support pop_options. */
# pragma GCC optimize ("O0")
#endif
/** Try to free a replaceable block.
@param limit maximum number of blocks to scan
@return true if found and freed */
bool buf_LRU_scan_and_free_block(ulint limit)
{
mysql_mutex_assert_owner(&buf_pool.mutex);
return buf_LRU_free_from_unzip_LRU_list(limit) ||
buf_LRU_free_from_common_LRU_list(limit);
}
#ifdef UNIV_DEBUG
/** Validate the LRU list. */
void buf_LRU_validate()
{
ulint old_len;
ulint new_len;
mysql_mutex_lock(&buf_pool.mutex);
if (UT_LIST_GET_LEN(buf_pool.LRU) >= BUF_LRU_OLD_MIN_LEN) {
ut_a(buf_pool.LRU_old);
old_len = buf_pool.LRU_old_len;
new_len = ut_min(UT_LIST_GET_LEN(buf_pool.LRU)
* buf_pool.LRU_old_ratio
/ BUF_LRU_OLD_RATIO_DIV,
UT_LIST_GET_LEN(buf_pool.LRU)
- (BUF_LRU_OLD_TOLERANCE
+ BUF_LRU_NON_OLD_MIN_LEN));
ut_a(old_len >= new_len - BUF_LRU_OLD_TOLERANCE);
ut_a(old_len <= new_len + BUF_LRU_OLD_TOLERANCE);
}
CheckInLRUList::validate();
old_len = 0;
for (buf_page_t* bpage = UT_LIST_GET_FIRST(buf_pool.LRU);
bpage != NULL;
bpage = UT_LIST_GET_NEXT(LRU, bpage)) {
ut_ad(bpage->in_file());
ut_ad(!bpage->frame
|| reinterpret_cast<buf_block_t*>(bpage)
->in_unzip_LRU_list
== bpage->belongs_to_unzip_LRU());
if (bpage->is_old()) {
const buf_page_t* prev
= UT_LIST_GET_PREV(LRU, bpage);
const buf_page_t* next
= UT_LIST_GET_NEXT(LRU, bpage);
if (!old_len++) {
ut_a(buf_pool.LRU_old == bpage);
} else {
ut_a(!prev || prev->is_old());
}
ut_a(!next || next->is_old());
}
}
ut_a(buf_pool.LRU_old_len == old_len);
CheckInFreeList::validate();
for (buf_page_t* bpage = UT_LIST_GET_FIRST(buf_pool.free);
bpage != NULL;
bpage = UT_LIST_GET_NEXT(list, bpage)) {
ut_a(bpage->state() == buf_page_t::NOT_USED);
}
CheckUnzipLRUAndLRUList::validate();
for (buf_block_t* block = UT_LIST_GET_FIRST(buf_pool.unzip_LRU);
block != NULL;
block = UT_LIST_GET_NEXT(unzip_LRU, block)) {
ut_ad(block->in_unzip_LRU_list);
ut_ad(block->page.in_LRU_list);
ut_a(block->page.belongs_to_unzip_LRU());
}
mysql_mutex_unlock(&buf_pool.mutex);
}
#endif /* UNIV_DEBUG */
#if defined UNIV_DEBUG_PRINT || defined UNIV_DEBUG
/** Dump the LRU list to stderr. */
void buf_LRU_print()
{
mysql_mutex_lock(&buf_pool.mutex);
for (buf_page_t* bpage = UT_LIST_GET_FIRST(buf_pool.LRU);
bpage != NULL;
bpage = UT_LIST_GET_NEXT(LRU, bpage)) {
const page_id_t id(bpage->id());
fprintf(stderr, "BLOCK space %u page %u ",
id.space(), id.page_no());
if (bpage->is_old()) {
fputs("old ", stderr);
}
const unsigned s = bpage->state();
if (s > buf_page_t::UNFIXED) {
fprintf(stderr, "fix %u ", s - buf_page_t::UNFIXED);
} else {
ut_ad(s == buf_page_t::UNFIXED
|| s == buf_page_t::REMOVE_HASH);
}
if (bpage->oldest_modification()) {
fputs("modif. ", stderr);
}
if (const byte* frame = bpage->zip.data) {
fprintf(stderr, "\ntype %u size " ULINTPF
" index id " IB_ID_FMT "\n",
fil_page_get_type(frame),
bpage->zip_size(),
btr_page_get_index_id(frame));
} else {
fprintf(stderr, "\ntype %u index id " IB_ID_FMT "\n",
fil_page_get_type(bpage->frame),
btr_page_get_index_id(bpage->frame));
}
}
mysql_mutex_unlock(&buf_pool.mutex);
}
#endif /* UNIV_DEBUG_PRINT || UNIV_DEBUG */
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