From: "Bang Li" <libang.li@antgroup.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
"朱辉(茶水)" <teawater@antgroup.com>,
"Yan Yan(cailing)" <yanyan.yan@antgroup.com>
Subject: Re: [PATCH] mm/compaction: Reduce unnecessary loops
Date: Sat, 13 Jan 2024 13:52:17 +0800 [thread overview]
Message-ID: <a15af04e-ed31-45a7-958c-8c727ee046db@antgroup.com> (raw)
In-Reply-To: <20240112112551.bbc9d5114fd2c6fb421fed2d@linux-foundation.org>
On 2024/1/13 3:25, Andrew Morton wrote:
> On Fri, 12 Jan 2024 15:35:24 +0800 "Bang Li" <libang.li@antgroup.com> wrote:
>
>> Compaction will be triggered when we write 1 to '/proc/sys/vm/
>> compact_memory'. During the execution of the process, when we send
>> SIGKILL to terminate the compaction, the process does not exit
>> immediately. Instead, it will continue to loop through the remaining
>> zones and nodes before exiting.
>>
>> in my environment:
>>
>> [root]# cat /proc/buddyinfo
>> Node 0, zone DMA 1 1 1 0 2 1 1 0 1 1 3
>> Node 0, zone DMA32 1666 1123 804 625 488 356 321 278 209 178 250
>> Node 0, zone Normal 58852 83160 49983 9812 2287 1229 19604 24471 10346 5219 12205
>> [root]# echo 1 > /sys/kernel/debug/tracing/events/compaction/mm_compaction_end/enable
>>
>> before the patch:
>>
>> [root]# timeout --signal=SIGKILL 0.002 bash -c 'echo 1 > /proc/sys/vm/compact_memory'
>> [root]# cat /sys/kernel/debug/tracing/trace_pipe
>> <...>-26494 [014] ..... 226.468993: mm_compaction_end: zone_start=0x1 migrate_pfn=0xe00 free_pfn=0xe00 zone_end=0x1000, mode=sync status=complete
>> <...>-26494 [014] ..... 226.469718: mm_compaction_end: zone_start=0x1000 migrate_pfn=0x20a80 free_pfn=0xffe00 zone_end=0x100000, mode=sync status=contended
>> <...>-26494 [014] ..... 226.469720: mm_compaction_end: zone_start=0x100000 migrate_pfn=0x100000 free_pfn=0x307fe00 zone_end=0x3080000, mode=sync status=contended
>>
>> after the patch:
>>
>> [root]# timeout --signal=SIGKILL 0.002 bash -c 'echo 1 > /proc/sys/vm/compact_memory'
>> [root]# cat /sys/kernel/debug/tracing/trace_pipe
>> <...>-17491 [053] ..... 109.005387: mm_compaction_end: zone_start=0x1 migrate_pfn=0xe00 free_pfn=0xe00 zone_end=0x1000, mode=sync status=complete
>> <...>-17491 [053] ..... 109.006139: mm_compaction_end: zone_start=0x1000 migrate_pfn=0x22220 free_pfn=0xffe00 zone_end=0x100000, mode=sync status=contended
>>
>> Although it exits quickly after receiving the SIGKILL signal, a better
>> solution is to terminate the loop early after receiving the SIGKILL
>> signal.
>>
>
> What is the use case here? The requirement? Why is this change
> valuable to anyone?
Thanks for the quick reply! I'm very sorry that my inappropriate use
case confused you. What I want to explain is that when receiving the
SIGKILL signal, we can break in advance to reduce unnecessary loops.
This is a clean up patch, the purpose is to reduce the execution of
unnecessary code. If possible, I will remove the confusing use case
in V2.
Thanks,
Bang
prev parent reply other threads:[~2024-01-13 5:52 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-12 7:35 [PATCH] mm/compaction: Reduce unnecessary loops Bang Li
2024-01-12 19:25 ` Andrew Morton
2024-01-13 5:52 ` Bang Li [this message]
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