From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: David Rientjes <rientjes@google.com>,
Suren Baghdasaryan <surenb@google.com>
Cc: akpm@linux-foundation.org, mhocko@suse.com, hannes@cmpxchg.org,
hillf.zj@alibaba-inc.com, minchan@kernel.org,
mgorman@techsingularity.net, ying.huang@intel.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
timmurray@google.com, tkjos@google.com
Subject: Re: [PATCH v2] mm: terminate shrink_slab loop if signal is pending
Date: Sat, 9 Dec 2017 21:44:20 +0900 [thread overview]
Message-ID: <f0f67f05-7efb-0e2a-071c-2ef87530bb79@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <alpine.DEB.2.10.1712081259520.47087@chino.kir.corp.google.com>
On 2017/12/09 6:02, David Rientjes wrote:
> On Thu, 7 Dec 2017, Suren Baghdasaryan wrote:
>
>> Slab shrinkers can be quite time consuming and when signal
>> is pending they can delay handling of the signal. If fatal
>> signal is pending there is no point in shrinking that process
>> since it will be killed anyway. This change checks for pending
>> fatal signals inside shrink_slab loop and if one is detected
>> terminates this loop early.
>>
>
> I've proposed a similar patch in the past, but for a check on TIF_MEMDIE,
> which would today be a tsk_is_oom_victim(current), since we had observed
> lengthy stalls in reclaim that would have been prevented if the oom victim
> had exited out, returned back to the page allocator, allocated with
> ALLOC_NO_WATERMARKS, and proceeded to quickly exit.
>
> I'm not sure that all fatal_signal_pending() tasks should get the same
> treatment, but I understand the point that the task is killed and should
> free memory when it fully exits. How much memory is unknown.
>
We can use __GFP_KILLABLE. Unless there is performance impact for checking
fatal_siganl_pending(), allowing only fatal_signal_pending() threads with
__GFP_KILLABLE to bail out (without using memory reserves) should be safe.
prev parent reply other threads:[~2017-12-09 12:44 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-08 1:23 [PATCH v2] mm: terminate shrink_slab loop if signal is pending Suren Baghdasaryan
2017-12-08 8:22 ` Michal Hocko
2017-12-08 11:36 ` Tetsuo Handa
2017-12-08 11:48 ` Michal Hocko
2017-12-08 14:03 ` Tetsuo Handa
2017-12-08 18:06 ` Suren Baghdasaryan
2017-12-09 8:08 ` Tetsuo Handa
2017-12-10 10:17 ` Michal Hocko
2017-12-11 21:05 ` Suren Baghdasaryan
2017-12-10 10:13 ` Michal Hocko
2017-12-10 11:37 ` Tetsuo Handa
2017-12-11 21:12 ` Suren Baghdasaryan
2017-12-08 21:02 ` David Rientjes
2017-12-09 3:16 ` Suren Baghdasaryan
2017-12-09 12:44 ` Tetsuo Handa [this message]
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