mirror/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2026-05-16 20:07:13 +02:00
Code Issues Projects Releases Packages Wiki Activity

MDEV-29967 innodb_read_ahead_threshold (linear read-ahead) does not work

Browse source 
buf_read_ahead_linear(): Correct some calculations that were broken
in commit b1ab211dee (MDEV-15053).

Thanks to Daniel Black for providing a test case and initial debugging.

Tested by: Matthias Leich
This commit is contained in:
Marko Mäkelä 2023-05-11 13:21:57 +03:00
commit 279d0120f5
1 changed files with 17 additions and 8 deletions
Download patch file Download diff file Expand all files Collapse all files

25
storage/innobase/buf/buf0rea.cc
View file

@ -582,7 +582,7 @@ buf_read_ahead_linear(const page_id_t page_id, ulint zip_size, bool ibuf)
/* We will check that almost all pages in the area have been accessed
in the desired order. */
const bool descending= page_id == low;
const bool descending= page_id != low;
if (!descending && page_id != high_1)
/* This is not a border page of the area */
@ -612,7 +612,7 @@ fail:
uint32_t{buf_pool.read_ahead_area});
page_id_t new_low= low, new_high_1= high_1;
unsigned prev_accessed= 0;
for (page_id_t i= low; i != high_1; ++i)
for (page_id_t i= low; i <= high_1; ++i)
{
const ulint fold= i.fold();
page_hash_latch *hash_lock= buf_pool.page_hash.lock<false>(fold);
@ -647,12 +647,21 @@ hard_fail:
if (prev == FIL_NULL || next == FIL_NULL)
goto hard_fail;
page_id_t id= page_id;
if (descending && next - 1 == page_id.page_no())
id.set_page_no(prev);
else if (!descending && prev + 1 == page_id.page_no())
id.set_page_no(next);
if (descending)
{
if (id == high_1)
++id;
else if (next - 1 != page_id.page_no())
goto hard_fail;
else
id.set_page_no(prev);
}
else
goto hard_fail; /* Successor or predecessor not in the right order */
{
if (prev + 1 != page_id.page_no())
goto hard_fail;
id.set_page_no(next);
}
new_low= id - (id.page_no() % buf_read_ahead_area);
new_high_1= new_low + (buf_read_ahead_area - 1);
@ -693,7 +702,7 @@ failed:
/* If we got this far, read-ahead can be sensible: do it */
count= 0;
for (ulint ibuf_mode= ibuf ? BUF_READ_IBUF_PAGES_ONLY : BUF_READ_ANY_PAGE;
new_low != new_high_1; ++new_low)
new_low <= new_high_1; ++new_low)
{
if (ibuf_bitmap_page(new_low, zip_size))
continue;