mirror of
https://github.com/MariaDB/server.git
synced 2025-06-10 23:04:44 +02:00
56e0be34bc
In commit b6923420f3 (MDEV-29445)
we started to specify the MAP_POPULATE flag for allocating the
InnoDB buffer pool. This would cause a lot of time to be spent
on __mm_populate() inside the Linux kernel, such as 16 seconds
to pre-fault or commit innodb_buffer_pool_size=64G.
Let us revert to the previous way of allocating the buffer pool
at startup. Note: An attempt to increase the buffer pool size by
SET GLOBAL innodb_buffer_pool_size (up to innodb_buffer_pool_size_max)
will invoke my_virtual_mem_commit(), which will use MAP_POPULATE
to zero-fill and prefault the requested additional memory area, blocking
buf_pool.mutex.
Before MDEV-29445 we allocated the InnoDB buffer pool by invoking
mmap(2) once (via my_large_malloc()). After the change, we would
invoke mmap(2) twice, first via my_virtual_mem_reserve() and then
via my_virtual_mem_commit(). Outside Microsoft Windows, we are
reverting back to my_large_malloc() like allocation.
my_virtual_mem_reserve(): Define only for Microsoft Windows.
Other platforms should invoke my_large_virtual_alloc() and
update_malloc_size() instead of my_virtual_mem_reserve() and
my_virtual_mem_commit().
my_large_virtual_alloc(): Define only outside Microsoft Windows.
Do not specify MAP_NORESERVE nor MAP_POPULATE, to preserve compatibility
with my_large_malloc(). Were MAP_POPULATE specified, the mmap()
system call would be significantly slower, for example 18 seconds
to reserve 64 GiB upfront.
37 lines
1.1 KiB
C
37 lines
1.1 KiB
C
/* Copyright (c) 2025, MariaDB
|
|
|
|
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 St, Fifth Floor, Boston, MA 02110-1335 USA */
|
|
|
|
#pragma once
|
|
/*
|
|
Functionality for handling virtual memory
|
|
(reserve, commit, decommit, release)
|
|
*/
|
|
#include <stddef.h> /*size_t*/
|
|
|
|
#ifdef __cplusplus
|
|
extern "C" {
|
|
#endif
|
|
|
|
# ifdef _WIN32
|
|
char *my_virtual_mem_reserve(size_t *size);
|
|
# endif
|
|
char *my_virtual_mem_commit(char *ptr, size_t size);
|
|
void my_virtual_mem_decommit(char *ptr, size_t size);
|
|
void my_virtual_mem_release(char *ptr, size_t size);
|
|
|
|
#ifdef __cplusplus
|
|
}
|
|
#endif
|
|
|