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arc_default_max on Linux should match FreeBSD 

Commits 518b487 and 23bdb07 changed the default ARC size limit on
Linux systems to 1/2 of physical memory, which has become too
strict for modern systems with large amounts of RAM. This patch
changes the default limit to match that of FreeBSD, so ZFS may
have a unified value on both platforms.

Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Edmund Nadolski <edmund.nadolski@ixsystems.com>
Closes #15437
This commit is contained in:
ednadolski-ix 2023-10-26 10:13:01 -06:00 committed by GitHub
parent 3afdc97d91
commit 6a629f3234
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2 changed files with 9 additions and 6 deletions
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5
man/man4/zfs.4
View File

@ -644,10 +644,7 @@ Max size of ARC in bytes.
If
.Sy 0 ,
then the max size of ARC is determined by the amount of system memory installed.
Under Linux, half of system memory will be used as the limit.
Under
.Fx ,
the larger of
The larger of
.Sy all_system_memory No \- Sy 1 GiB
and
.Sy 5/8 No \(mu Sy all_system_memory

10
module/os/linux/zfs/arc_os.c
View File

@ -80,12 +80,18 @@ static struct notifier_block arc_hotplug_callback_mem_nb;
/*
* Return a default max arc size based on the amount of physical memory.
* This may be overridden by tuning the zfs_arc_max module parameter.
*/
uint64_t
arc_default_max(uint64_t min, uint64_t allmem)
{
/* Default to 1/2 of all memory. */
return (MAX(allmem / 2, min));
uint64_t size;
if (allmem >= 1 << 30)
size = allmem - (1 << 30);
else
size = min;
return (MAX(allmem * 5 / 8, size));
}
#ifdef _KERNEL