linux-mm.kvack.org archive mirror
 help / color / mirror / Atom feed
From: Mel Gorman <mgorman@suse.de>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	kernel-team@fb.com
Subject: Re: [PATCH] mm: don't wake kswapd prematurely when watermark boosting is disabled
Date: Tue, 20 Oct 2020 21:33:31 +0100	[thread overview]
Message-ID: <20201020203331.GB32041@suse.de> (raw)
In-Reply-To: <20201020175833.397286-1-hannes@cmpxchg.org>

On Tue, Oct 20, 2020 at 01:58:33PM -0400, Johannes Weiner wrote:
> On 2-node NUMA hosts we see bursts of kswapd reclaim and subsequent
> pressure spikes and stalls from cache refaults while there is plenty
> of free memory in the system.
> 
> Usually, kswapd is woken up when all eligible nodes in an allocation
> are full. But the code related to watermark boosting can wake kswapd
> on one full node while the other one is mostly empty. This may be
> justified to fight fragmentation, but is currently unconditionally
> done whether watermark boosting is occurring or not.
> 
> In our case, many of our workloads' throughput scales with available
> memory, and pure utilization is a more tangible concern than trends
> around longer-term fragmentation. As a result we generally disable
> watermark boosting.
> 
> Wake kswapd only woken when watermark boosting is requested.
> 
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>

This makes sense to the extent that I would support adding

Fixes: 1c30844d2dfe ("mm: reclaim small amounts of memory when an external fragmentation event occurs")

With or without that;

Acked-by: Mel Gorman <mgorman@suse.de>

-- 
Mel Gorman
SUSE Labs


      reply	other threads:[~2020-10-20 20:33 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-20 17:58 Johannes Weiner
2020-10-20 20:33 ` Mel Gorman [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20201020203331.GB32041@suse.de \
    --to=mgorman@suse.de \
    --cc=akpm@linux-foundation.org \
    --cc=hannes@cmpxchg.org \
    --cc=kernel-team@fb.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --subject='Re: [PATCH] mm: don'\''t wake kswapd prematurely when watermark boosting is disabled' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).