linux-kernel - Re: [PATCH] locking/ww_mutex: Replace cpu_relax with cond

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Message-ID: <20170228094853.GF6500@twins.programming.kicks-ass.net>
Date:   Tue, 28 Feb 2017 10:48:53 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Chris Wilson <chris@...is-wilson.co.uk>
Cc:     linux-kernel@...r.kernel.org, Fengguang Wu <fengguang.wu@...el.com>
Subject: Re: [PATCH] locking/ww_mutex: Replace cpu_relax with cond_resched
 for tests

On Tue, Feb 28, 2017 at 09:40:11AM +0000, Chris Wilson wrote:
> When busy-spinning on a ww_mutex_trylock(), we depend upon the other
> thread advancing and releasing the lock. This can not happen on a single
> CPU unless we relinquish it.

Thanks, do you have any clue about those other ww-mutex test fails? So
far I've not had much luck poking at them.