From: Peter Zijlstra <peterz@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Daniel Wagner <wagi@monom.org>, Ingo Molnar <mingo@kernel.org>,
Oleg Nesterov <oleg@redhat.com>,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
Tejun Heo <tj@kernel.org>, Ingo Molnar <mingo@redhat.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
der.herr@hofr.at, Davidlohr Bueso <dave@stgolabs.net>,
Rik van Riel <riel@redhat.com>, Al Viro <viro@zeniv.linux.org.uk>,
Jeff Layton <jlayton@poochiereds.net>
Subject: Re: [RFC][PATCH 00/13] percpu rwsem -v2
Date: Thu, 2 Jul 2015 11:41:55 +0200 [thread overview]
Message-ID: <20150702094155.GW19282@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <CA+55aFy0nKSbr6YRUV62Ns9E53yJ9Wf1KHd2+mh+G12Co-tsiA@mail.gmail.com>
On Wed, Jul 01, 2015 at 02:54:59PM -0700, Linus Torvalds wrote:
> On Tue, Jun 30, 2015 at 10:57 PM, Daniel Wagner <wagi@monom.org> wrote:
> >
> > And an attempt at visualization:
> >
> > http://monom.org/posix01/sweep-4.1.0-02756-ge3d06bd.png
> > http://monom.org/posix01/sweep-4.1.0-02769-g6ce2591.png
>
> Ugh. The old numbers look (mostly) fairly tight, and then the new ones
> are all over the map, and usually much worse.
>
> We've seen this behavior before when switching from a non-sleeping
> lock to a sleeping one. The sleeping locks have absolutely horrible
> behavior when they get contended, and spend tons of CPU time on the
> sleep/wakeup management,
Right, I'm just not seeing how any of that would happen here :/ The read
side would only ever block on reading /proc/$something and I'm fairly
sure that benchmark doesn't actually touch that file.
In any case, I will look into this, I've just not had time yet..
next prev parent reply other threads:[~2015-07-02 9:42 UTC|newest]
Thread overview: 106+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-22 12:16 [RFC][PATCH 00/13] percpu rwsem -v2 Peter Zijlstra
2015-06-22 12:16 ` [RFC][PATCH 01/13] rcu: Create rcu_sync infrastructure Peter Zijlstra
2015-06-22 12:16 ` [RFC][PATCH 02/13] rcusync: Introduce struct rcu_sync_ops Peter Zijlstra
2015-06-22 12:16 ` [RFC][PATCH 03/13] rcusync: Add the CONFIG_PROVE_RCU checks Peter Zijlstra
2015-06-22 12:16 ` [RFC][PATCH 04/13] rcusync: Introduce rcu_sync_dtor() Peter Zijlstra
2015-06-22 12:16 ` [RFC][PATCH 05/13] percpu-rwsem: Optimize readers and reduce global impact Peter Zijlstra
2015-06-22 23:02 ` Oleg Nesterov
2015-06-23 7:28 ` Nicholas Mc Guire
2015-06-25 19:08 ` Peter Zijlstra
2015-06-25 19:17 ` Tejun Heo
2015-06-29 9:32 ` Peter Zijlstra
2015-06-29 15:12 ` Tejun Heo
2015-06-29 15:14 ` Peter Zijlstra
2015-06-22 12:16 ` [RFC][PATCH 06/13] percpu-rwsem: Provide percpu_down_read_trylock() Peter Zijlstra
2015-06-22 23:08 ` Oleg Nesterov
2015-06-22 12:16 ` [RFC][PATCH 07/13] sched: Reorder task_struct Peter Zijlstra
2015-06-22 12:16 ` [RFC][PATCH 08/13] percpu-rwsem: DEFINE_STATIC_PERCPU_RWSEM Peter Zijlstra
2015-06-22 12:16 ` [RFC][PATCH 09/13] hotplug: Replace hotplug lock with percpu-rwsem Peter Zijlstra
2015-06-22 22:57 ` Oleg Nesterov
2015-06-23 7:16 ` Peter Zijlstra
2015-06-23 17:01 ` Oleg Nesterov
2015-06-23 17:53 ` Peter Zijlstra
2015-06-24 13:50 ` Oleg Nesterov
2015-06-24 14:13 ` Peter Zijlstra
2015-06-24 15:12 ` Oleg Nesterov
2015-06-24 16:15 ` Peter Zijlstra
2015-06-28 23:56 ` [PATCH 0/3] percpu-rwsem: introduce percpu_rw_semaphore->recursive mode Oleg Nesterov
2015-06-28 23:56 ` [PATCH 1/3] rcusync: introduce rcu_sync_struct->exclusive mode Oleg Nesterov
2015-06-28 23:56 ` [PATCH 2/3] percpu-rwsem: don't use percpu_rw_semaphore->rw_sem to exclude writers Oleg Nesterov
2015-06-28 23:56 ` [PATCH 3/3] percpu-rwsem: introduce percpu_rw_semaphore->recursive mode Oleg Nesterov
2015-06-22 12:16 ` [RFC][PATCH 10/13] fs/locks: Replace lg_global with a percpu-rwsem Peter Zijlstra
2015-06-22 12:16 ` [RFC][PATCH 11/13] fs/locks: Replace lg_local with a per-cpu spinlock Peter Zijlstra
2015-06-23 0:19 ` Oleg Nesterov
2015-06-22 12:16 ` [RFC][PATCH 12/13] stop_machine: Remove lglock Peter Zijlstra
2015-06-22 22:21 ` Oleg Nesterov
2015-06-23 10:09 ` Peter Zijlstra
2015-06-23 10:55 ` Peter Zijlstra
2015-06-23 11:20 ` Peter Zijlstra
2015-06-23 13:08 ` Peter Zijlstra
2015-06-23 16:36 ` Oleg Nesterov
2015-06-23 17:30 ` Paul E. McKenney
2015-06-23 18:04 ` Peter Zijlstra
2015-06-23 18:26 ` Paul E. McKenney
2015-06-23 19:05 ` Paul E. McKenney
2015-06-24 2:23 ` Paul E. McKenney
2015-06-24 8:32 ` Peter Zijlstra
2015-06-24 9:31 ` Peter Zijlstra
2015-06-24 13:48 ` Paul E. McKenney
2015-06-24 15:01 ` Paul E. McKenney
2015-06-24 15:34 ` Peter Zijlstra
2015-06-24 7:35 ` Peter Zijlstra
2015-06-24 8:42 ` Ingo Molnar
2015-06-24 13:39 ` Paul E. McKenney
2015-06-24 13:43 ` Ingo Molnar
2015-06-24 14:03 ` Paul E. McKenney
2015-06-24 14:50 ` Paul E. McKenney
2015-06-24 15:01 ` Peter Zijlstra
2015-06-24 15:27 ` Paul E. McKenney
2015-06-24 15:40 ` Peter Zijlstra
2015-06-24 16:09 ` Paul E. McKenney
2015-06-24 16:42 ` Peter Zijlstra
2015-06-24 17:10 ` Paul E. McKenney
2015-06-24 17:20 ` Paul E. McKenney
2015-06-24 17:29 ` Peter Zijlstra
2015-06-24 17:28 ` Peter Zijlstra
2015-06-24 17:32 ` Peter Zijlstra
2015-06-24 18:14 ` Peter Zijlstra
2015-06-24 17:58 ` Peter Zijlstra
2015-06-25 3:23 ` Paul E. McKenney
2015-06-25 11:07 ` Peter Zijlstra
2015-06-25 13:47 ` Paul E. McKenney
2015-06-25 14:20 ` Peter Zijlstra
2015-06-25 14:51 ` Paul E. McKenney
2015-06-26 12:32 ` Peter Zijlstra
2015-06-26 16:14 ` Paul E. McKenney
2015-06-29 7:56 ` Peter Zijlstra
2015-06-30 21:32 ` Paul E. McKenney
2015-07-01 11:56 ` Peter Zijlstra
2015-07-01 15:56 ` Paul E. McKenney
2015-07-01 16:16 ` Peter Zijlstra
2015-07-01 18:45 ` Paul E. McKenney
2015-06-23 14:39 ` Paul E. McKenney
2015-06-23 16:20 ` Oleg Nesterov
2015-06-23 17:24 ` Oleg Nesterov
2015-06-25 19:18 ` Peter Zijlstra
2015-06-22 12:16 ` [RFC][PATCH 13/13] locking: " Peter Zijlstra
2015-06-22 12:36 ` [RFC][PATCH 00/13] percpu rwsem -v2 Peter Zijlstra
2015-06-22 18:11 ` Daniel Wagner
2015-06-22 19:05 ` Peter Zijlstra
2015-06-23 9:35 ` Daniel Wagner
2015-06-23 10:00 ` Ingo Molnar
2015-06-23 14:34 ` Peter Zijlstra
2015-06-23 14:56 ` Daniel Wagner
2015-06-23 17:50 ` Peter Zijlstra
2015-06-23 19:36 ` Peter Zijlstra
2015-06-24 8:46 ` Ingo Molnar
2015-06-24 9:01 ` Peter Zijlstra
2015-06-24 9:18 ` Daniel Wagner
2015-07-01 5:57 ` Daniel Wagner
2015-07-01 21:54 ` Linus Torvalds
2015-07-02 9:41 ` Peter Zijlstra [this message]
2015-07-20 5:53 ` Daniel Wagner
2015-07-20 18:44 ` Linus Torvalds
2015-06-22 20:06 ` Linus Torvalds
2015-06-23 16:10 ` Davidlohr Bueso
2015-06-23 16:21 ` Peter Zijlstra
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