linux-kernel - Re: [PATCH] mm: add maybe_lru_add_drain() that only drains when threshold is exceeded

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] [day] [month] [year] [list]

Message-ID: <ca363982c86fa57fe35b4723930a5d1f43e4210a.camel@surriel.com>
Date: Thu, 19 Dec 2024 12:50:00 -0500
From: Rik van Riel <riel@...riel.com>
To: David Hildenbrand <david@...hat.com>, Andrew Morton
	 <akpm@...ux-foundation.org>
Cc: Chris Li <chrisl@...nel.org>, Ryan Roberts <ryan.roberts@....com>, 
 "Matthew Wilcox (Oracle)"
	 <willy@...radead.org>, linux-kernel@...r.kernel.org, linux-mm@...ck.org, 
	kernel-team@...a.com
Subject: Re: [PATCH] mm: add maybe_lru_add_drain() that only drains when
 threshold is exceeded

On Thu, 2024-12-19 at 18:23 +0100, David Hildenbrand wrote:
> On 19.12.24 15:11, Rik van Riel wrote:
> > 
> > I think we need to free those pending pages at
> > some point. They can't accumulate there forever.
> > However, I am not sure where those points should
> > be.
> 
> The number of entries are limited, 

...
> folio_batch_add() drains if folio_batch_space() returns 0 (no slots
> left).
> 
> Apparently we have PAGEVEC_SIZE slots, which is 31 ... 31 * PAGE_SIZE
> stranded there.

Sure enough! That was the piece I was missing last night.

I guess we can get away with just draining these in the
reclaim and compaction paths, and not touch them the
rest of the time?

That could be a nice improvement in some situations.

-- 
All Rights Reversed.