linux-kernel - Re: [patch 3/8] mm: vmscan: save work scanning (almost) empty LRU lists

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]

Date:	Thu, 13 Dec 2012 14:33:32 -0500
From:	Johannes Weiner <hannes@...xchg.org>
To:	Mel Gorman <mgorman@...e.de>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Rik van Riel <riel@...hat.com>,
	Michal Hocko <mhocko@...e.cz>, Hugh Dickins <hughd@...gle.com>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [patch 3/8] mm: vmscan: save work scanning (almost) empty LRU
 lists

On Thu, Dec 13, 2012 at 10:41:04AM +0000, Mel Gorman wrote:
> On Wed, Dec 12, 2012 at 04:43:35PM -0500, Johannes Weiner wrote:
> > In certain cases (kswapd reclaim, memcg target reclaim), a fixed
> > minimum amount of pages is scanned from the LRU lists on each
> > iteration, to make progress.
> > 
> > Do not make this minimum bigger than the respective LRU list size,
> > however, and save some busy work trying to isolate and reclaim pages
> > that are not there.
> > 
> > Signed-off-by: Johannes Weiner <hannes@...xchg.org>
> 
> This looks like a corner case where the LRU size would have to be smaller
> than SWAP_CLUSTER_MAX. Is that common enough to care? It looks correct,
> I'm just curious.

We have one lruvec per memcg per zone, so consider memory cgroups in a
NUMA environment: NR_MEMCG * (NR_NODES - 1) * NR_LRU_LISTS permanently
empty lruvecs, assuming the memory of one cgroup is bound to one node.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/