Re: [PATCH] mm: Stop kswapd early when nothing's waiting for it to free pages

From: Andrew Morton
Date: Wed Feb 19 2020 - 14:26:57 EST

On Wed, 19 Feb 2020 10:25:22 -0800 Sultan Alsawaf <sultan@xxxxxxxxxxxxxxx> wrote:

> Keeping kswapd running when all the failed allocations that invoked it
> are satisfied incurs a high overhead due to unnecessary page eviction
> and writeback, as well as spurious VM pressure events to various
> registered shrinkers. When kswapd doesn't need to work to make an
> allocation succeed anymore, stop it prematurely to save resources.

Seems sensible.

Please fully describe the userspace-visible runtime effects of this