From: Roman Penyaev <rpenyaev@suse.de>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: hev <r@hev.cc>,
linux-fsdevel@vger.kernel.org, Al Viro <viro@zeniv.linux.org.uk>,
Davide Libenzi <davidel@xmailserver.org>,
Davidlohr Bueso <dave@stgolabs.net>,
Dominik Brodowski <linux@dominikbrodowski.net>,
Eric Wong <e@80x24.org>, Jason Baron <jbaron@akamai.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Sridhar Samudrala <sridhar.samudrala@intel.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH RESEND v4] fs/epoll: Remove unnecessary wakeups of nested epoll that in ET mode
Date: Sat, 28 Sep 2019 21:07:26 +0200 [thread overview]
Message-ID: <ddd241902bef0062ed648f4eb2e5ec0e@suse.de> (raw)
In-Reply-To: <20190927192915.6ec24ad706258de99470a96e@linux-foundation.org>
On 2019-09-28 04:29, Andrew Morton wrote:
> On Wed, 25 Sep 2019 09:56:03 +0800 hev <r@hev.cc> wrote:
>
>> From: Heiher <r@hev.cc>
>>
>> Take the case where we have:
>>
>> t0
>> | (ew)
>> e0
>> | (et)
>> e1
>> | (lt)
>> s0
>>
>> t0: thread 0
>> e0: epoll fd 0
>> e1: epoll fd 1
>> s0: socket fd 0
>> ew: epoll_wait
>> et: edge-trigger
>> lt: level-trigger
>>
>> We only need to wakeup nested epoll fds if something has been queued
>> to the
>> overflow list, since the ep_poll() traverses the rdllist during
>> recursive poll
>> and thus events on the overflow list may not be visible yet.
>>
>> Test code:
>
> Look sane to me. Do you have any performance testing results which
> show a benefit?
>
> epoll maintainership isn't exactly a hive of activity nowadays :(
> Roman, would you please have time to review this?
Yes, I can revisit this once more next week.
Heiher, mind to prepare a patchset with your test suit and make it a
part
of kselftest? I hope nobody has any objections.
--
Roman
next prev parent reply other threads:[~2019-09-28 19:07 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-25 1:56 [PATCH RESEND v4] fs/epoll: Remove unnecessary wakeups of nested epoll that in ET mode hev
2019-09-28 2:29 ` Andrew Morton
2019-09-28 19:07 ` Roman Penyaev [this message]
2019-09-30 11:55 ` Roman Penyaev
2019-10-03 16:13 ` Jason Baron
2019-10-07 10:54 ` Roman Penyaev
2019-10-07 16:42 ` Jason Baron
2019-10-07 18:30 ` Roman Penyaev
2019-10-07 18:43 ` Jason Baron
2019-10-07 19:10 ` Roman Penyaev
2019-10-09 6:03 ` Heiher
2019-10-08 9:55 ` Roman Penyaev
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