linux-kernel - Re: [PATCH 6/6] mm: compaction: skip fast freepages isolation if enough freepages are isolated

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <efc76ea3-9a85-96a3-f3d7-212aeea7cf1c@suse.cz>
Date:   Tue, 30 May 2023 10:32:04 +0200
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Baolin Wang <baolin.wang@...ux.alibaba.com>,
        akpm@...ux-foundation.org
Cc:     mgorman@...hsingularity.net, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/6] mm: compaction: skip fast freepages isolation if
 enough freepages are isolated

On 5/25/23 14:54, Baolin Wang wrote:
> I've observed that fast isolation often isolates more pages than
> cc->migratepages, and the excess freepages will be released back to the
> buddy system. So skip fast freepages isolation if enough freepages are
> isolated to save some CPU cycles.
> 
> Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>

Acked-by: Vlastimil Babka <vbabka@...e.cz>

> ---
>  mm/compaction.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/mm/compaction.c b/mm/compaction.c
> index eccec84dae82..3ade4c095ed2 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -1550,6 +1550,10 @@ static void fast_isolate_freepages(struct compact_control *cc)
>  
>  		spin_unlock_irqrestore(&cc->zone->lock, flags);
>  
> +		/* Skip fast search if enough freepages isolated */
> +		if (cc->nr_freepages >= cc->nr_migratepages)
> +			break;
> +
>  		/*
>  		 * Smaller scan on next order so the total scan is related
>  		 * to freelist_scan_limit.