From: Peter Zijlstra <peterz@infradead.org>
To: Davidlohr Bueso <dave@stgolabs.net>
Cc: mingo@kernel.org, will@kernel.org, oleg@redhat.com,
tglx@linutronix.de, linux-kernel@vger.kernel.org,
bigeasy@linutronix.de, juri.lelli@redhat.com,
williams@redhat.com, bristot@redhat.com, longman@redhat.com,
jack@suse.com
Subject: Re: [PATCH 5/5] locking/percpu-rwsem: Remove the embedded rwsem
Date: Tue, 17 Dec 2019 11:35:47 +0100 [thread overview]
Message-ID: <20191217103547.GC2844@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20191118195304.b3d6fg4jmmj7kmfh@linux-p48b>
On Mon, Nov 18, 2019 at 11:53:04AM -0800, Davidlohr Bueso wrote:
> On Wed, 13 Nov 2019, Peter Zijlstra wrote:
> > @@ -54,23 +52,23 @@ static bool __percpu_down_read_trylock(s
> > * the same CPU as the increment, avoiding the
> > * increment-on-one-CPU-and-decrement-on-another problem.
>
> Nit: Now that you've made read_count more symmetric, maybe this first
> paragraph can be moved down to __percpu_rwsem_trylock() reader side,
> as such:
>
> /*
> * Due to having preemption disabled the decrement happens on
> * the same CPU as the increment, avoiding the
> * increment-on-one-CPU-and-decrement-on-another problem.
> */
> preempt_disable();
> ret = __percpu_down_read_trylock(sem);
> preempt_enable();
There's another callsite for that function too, so I think the current
place still works best.
next prev parent reply other threads:[~2019-12-17 10:35 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-13 10:21 [PATCH 0/5] locking: Percpu-rwsem rewrite Peter Zijlstra
2019-11-13 10:21 ` [PATCH 1/5] locking/percpu-rwsem, lockdep: Make percpu-rwsem use its own lockdep_map Peter Zijlstra
2019-11-15 20:39 ` Davidlohr Bueso
2020-01-08 1:33 ` [PATCH] locking/percpu-rwsem: Add might_sleep() for writer locking Davidlohr Bueso
2020-01-08 1:33 ` Davidlohr Bueso
2020-02-11 12:48 ` [tip: locking/core] " tip-bot2 for Davidlohr Bueso
2019-11-13 10:21 ` [PATCH 2/5] locking/percpu-rwsem: Convert to bool Peter Zijlstra
2019-11-13 10:21 ` [PATCH 3/5] locking/percpu-rwsem: Move __this_cpu_inc() into the slowpath Peter Zijlstra
2019-11-13 10:21 ` [PATCH 4/5] locking/percpu-rwsem: Extract __percpu_down_read_trylock() Peter Zijlstra
2019-11-18 16:28 ` Oleg Nesterov
2019-11-13 10:21 ` [PATCH 5/5] locking/percpu-rwsem: Remove the embedded rwsem Peter Zijlstra
2019-11-18 19:53 ` Davidlohr Bueso
2019-11-18 23:19 ` Davidlohr Bueso
2019-12-17 10:45 ` Peter Zijlstra
2019-12-17 10:35 ` Peter Zijlstra [this message]
2019-11-18 21:52 ` Waiman Long
2019-12-17 10:28 ` Peter Zijlstra
2019-11-19 13:50 ` Waiman Long
2019-11-19 15:58 ` Oleg Nesterov
2019-11-19 16:28 ` Waiman Long
2019-12-17 10:26 ` Peter Zijlstra
2019-12-17 10:28 ` Peter Zijlstra
2019-11-15 17:14 ` [PATCH 0/5] locking: Percpu-rwsem rewrite Juri Lelli
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