From: Roman Gushchin <guro@fb.com>
To: linux-mm@kvack.org
Cc: Tejun Heo <tj@kernel.org>, Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>, Shaohua Li <shli@fb.com>,
Rik van Riel <riel@surriel.com>,
linux-kernel@vger.kernel.org, cgroups@vger.kernel.org
Subject: Re: [RFC] mm: allow to decrease swap.max below actual swap usage
Date: Thu, 5 Apr 2018 15:47:50 +0100 [thread overview]
Message-ID: <20180405144744.GA15097@castle.DHCP.thefacebook.com> (raw)
In-Reply-To: <20180320223543.6188-1-guro@fb.com>
On Tue, Mar 20, 2018 at 10:35:43PM +0000, Roman Gushchin wrote:
> Currently an attempt to set swap.max into a value lower
> than the actual swap usage fails. And a user can't do much
> with it, except turning off swap globally (using swapoff).
>
> This patch aims to fix this issue by allowing setting swap.max
> into any value (which corresponds to cgroup v2 API design),
> and schedule a background job to fit swap size into the new limit.
>
> The following script can be used to test the memory.swap behavior:
> #!/bin/bash
>
> mkdir -p /sys/fs/cgroup/test_swap
> echo 100M > /sys/fs/cgroup/test_swap/memory.max
> echo max > /sys/fs/cgroup/test_swap/memory.swap.max
>
> mkdir -p /sys/fs/cgroup/test_swap_2
> echo 100M > /sys/fs/cgroup/test_swap_2/memory.max
> echo max > /sys/fs/cgroup/test_swap_2/memory.swap.max
>
> echo $$ > /sys/fs/cgroup/test_swap/cgroup.procs
> allocate 200M &
>
> echo $$ > /sys/fs/cgroup/test_swap_2/cgroup.procs
> allocate 200M &
>
> sleep 2
>
> cat /sys/fs/cgroup/test_swap/memory.swap.current
> cat /sys/fs/cgroup/test_swap_2/memory.swap.current
>
> echo max > /sys/fs/cgroup/test_swap/memory.max
> echo 50M > /sys/fs/cgroup/test_swap/memory.swap.max
>
> sleep 10
>
> cat /sys/fs/cgroup/test_swap/memory.swap.current
> cat /sys/fs/cgroup/test_swap_2/memory.swap.current
>
> pkill allocate
>
> Original test results:
> 106024960
> 106348544
> ./swap.sh: line 23: echo: write error: Device or resource busy
> 106024960
> 106348544
>
> With this patch applied:
> 106045440
> 106352640
> 52428800
> 106201088
Any comments, thoughts, feedback?
Rebased version below.
---
prev parent reply other threads:[~2018-04-05 14:48 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-20 22:35 Roman Gushchin
2018-04-05 14:47 ` Roman Gushchin [this message]
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