From: Siddhesh Poyarekar <siddhesh@sourceware.org>
To: libc-alpha@sourceware.org, Nicolas Dusart <nicolas@freedelity.be>
Subject: Re: [PATCH] realloc: Limit chunk reuse to only growing requests [BZ #30579]
Date: Wed, 5 Jul 2023 10:37:17 -0400 [thread overview]
Message-ID: <ba27e356-f944-1dd5-c2ab-45d9458737ec@sourceware.org> (raw)
In-Reply-To: <ZKVaLqbM3m7h9T7/@aurel32.net>
On 2023-07-05 07:55, Aurelien Jarno wrote:
> Hi,
>
> On 2023-07-04 14:24, Siddhesh Poyarekar via Libc-alpha wrote:
>> The trim_threshold is too aggressive a heuristic to decide if chunk
>> reuse is OK for reallocated memory; for repeated small, shrinking
>> allocations it leads to internal fragmentation and for repeated larger
>> allocations that fragmentation may blow up even worse due to the dynamic
>> nature of the threshold.
>>
>> Limit reuse only when it is within the alignment padding, which is 2 *
>> size_t for heap allocations and a page size for mmapped allocations.
>> There's the added wrinkle of THP, but this fix ignores it for now,
>> pessimizing that case in favor of keeping fragmentation low.
>>
>> This resolves BZ #30579.
>>
>> Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
>> Reported-by: Nicolas Dusart <nicolas@freedelity.be>
>> Reported-by: Aurelien Jarno <aurelien@aurel32.net>
>> ---
>>
>> The test case in the bz seems fixed with this, bringing VSZ and RSS back
>> to ~40M from ~1G. Aurelien, can you please test with plasma desktop?
>
> Thanks for the quick fix. I confirm that this patch fixes the issue with
> plasma desktop.
Thanks, if you think the fix is OK, can you please give a Reviewed-by?
I will then backport this to the 2.37 branch as well.
Thanks,
Sid
next prev parent reply other threads:[~2023-07-05 14:37 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-04 18:24 Siddhesh Poyarekar
2023-07-05 7:08 ` Nicolas Dusart
2023-07-05 10:46 ` Siddhesh Poyarekar
2023-07-05 11:55 ` Aurelien Jarno
2023-07-05 14:37 ` Siddhesh Poyarekar [this message]
2023-07-05 18:30 ` Aurelien Jarno
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