From: Mel Gorman <email@example.com> To: Johannes Weiner <firstname.lastname@example.org> Cc: Andrew Morton <email@example.com>, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org 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: <email@example.com> 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 <firstname.lastname@example.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 <email@example.com> -- Mel Gorman SUSE Labs
prev parent 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]
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