linux-kernel - Re: [PATCH 02/10] locking/qspinlock: Remove unbounded cmpxchg loop from locking slowpath

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Message-ID: <20180407090754.GP4082@hirez.programming.kicks-ass.net>
Date:   Sat, 7 Apr 2018 11:07:54 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Waiman Long <longman@...hat.com>
Cc:     Will Deacon <will.deacon@....com>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, mingo@...nel.org,
        boqun.feng@...il.com, paulmck@...ux.vnet.ibm.com,
        catalin.marinas@....com
Subject: Re: [PATCH 02/10] locking/qspinlock: Remove unbounded cmpxchg loop
 from locking slowpath

On Fri, Apr 06, 2018 at 04:50:19PM -0400, Waiman Long wrote:
>   # of threads  4.16 kernel     patched 4.16 kernel
>   ------------  -----------     -------------------
>         1       7,417 kop/s         7,408 kop/s
>         2       5,755 kop/s         4,486 kop/s
>         3       4,214 kop/s         4,169 kop/s
>         4       4,396 kop/s         4,383 kop/s
>        

Interesting, I didn't see that dip in my userspace tests.. I'll have to
try again.