From: Om Dhyade <odhyade@codeaurora.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Ingo Molnar <mingo@kernel.org>,
lkml <linux-kernel@vger.kernel.org>, Tejun Heo <tj@kernel.org>,
Dmitry Shmidt <dimitrysh@google.com>,
Rom Lemarchand <romlem@google.com>,
Colin Cross <ccross@google.com>, Todd Kjos <tkjos@google.com>
Subject: Re: [PATCH v2] locking/percpu-rwsem: Optimize readers and reduce global impact
Date: Fri, 12 Aug 2016 18:44:28 -0700 [thread overview]
Message-ID: <a720d3c9-b830-17b2-412b-549c4445d638@codeaurora.org> (raw)
In-Reply-To: <5a2cc178ee03466fa3b104f8f28b44ff@NASANEXM02C.na.qualcomm.com>
Thank you Dimtry for sharing the patches.
Update from my tests:
Use-case: Android application launches.
I tested the patches on android N build, i see max latency ~7ms.
In my tests, the wait is due to: copy_process(fork.c) blocks all threads
in __cgroup_procs_write including threads which are not part of the
forking process's thread-group.
Dimtry had provided a hack patch which reverts to per-process rw-sem
which had max latency of ~2ms.
android user-space binder library does 2 cgroup write operations per
transaction, apart from the copy_process(fork.c) wait, i see pre-emption
in _cgroup_procs_write causing waits.
Thanks.
--
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
next prev parent reply other threads:[~2016-08-13 1:44 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-09 9:51 Peter Zijlstra
2016-08-09 23:47 ` John Stultz
2016-08-10 7:56 ` Peter Zijlstra
2016-08-10 17:09 ` Oleg Nesterov
[not found] ` <CAH7ZN-zXrenrbbcmvZ+biNozYe21jw6fULopG=g9-xRwWHE6nw@mail.gmail.com>
[not found] ` <5a2cc178ee03466fa3b104f8f28b44ff@NASANEXM02C.na.qualcomm.com>
2016-08-13 1:44 ` Om Dhyade [this message]
2016-08-24 21:16 ` John Stultz
2016-08-24 21:30 ` Tejun Heo
2016-08-24 22:50 ` John Stultz
2016-08-26 2:14 ` John Stultz
2016-08-26 12:51 ` Tejun Heo
2016-08-26 16:47 ` Dmitry Shmidt
2016-08-26 20:10 ` Om Dhyade
2016-08-11 16:54 ` [PATCH] cgroup: avoid synchronize_sched() in __cgroup_procs_write() Oleg Nesterov
2016-08-18 10:59 ` [tip:locking/core] locking, rcu, cgroup: Avoid " tip-bot for Peter Zijlstra
2016-08-18 13:41 ` tip-bot for Peter Zijlstra
2016-08-31 5:21 ` [v2] locking/percpu-rwsem: Optimize readers and reduce global impact Guenter Roeck
2016-08-31 8:09 ` Peter Zijlstra
2016-08-31 13:41 ` Guenter Roeck
2016-08-31 13:47 ` Guenter Roeck
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