From: David Miller <davem@davemloft.net>
To: borntraeger@de.ibm.com
Cc: peterz@infradead.org, npiggin@gmail.com,
linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
linux-arch@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
heiko.carstens@de.ibm.com, schwidefsky@de.ibm.com,
noamc@ezchip.com
Subject: Re: [PATCH/RFC 0/5] cpu_relax: introduce yield, remove lowlatency
Date: Fri, 21 Oct 2016 10:57:27 -0400 (EDT) [thread overview]
Message-ID: <20161021.105727.140184460493941551.davem@davemloft.net> (raw)
In-Reply-To: <1477051138-1610-1-git-send-email-borntraeger@de.ibm.com>
From: Christian Borntraeger <borntraeger@de.ibm.com>
Date: Fri, 21 Oct 2016 13:58:53 +0200
> For spinning loops people did often use barrier() or cpu_relax().
> For most architectures cpu_relax and barrier are the same, but on
> some architectures cpu_relax can add some latency. For example on s390
> cpu_relax gives up the time slice to the hypervisor. On power cpu_relax
> tries to give some of the CPU to the neighbor threads. To reduce the
> latency another variant cpu_relax_lowlatency was introduced. Before this
> is used in more and more places, lets revert the logic of provide a new
> function cpu_relax_yield that can spend some time and for s390 yields
> the guest CPU.
Sparc64, fwiw, behaves similarly to powerpc.
next prev parent reply other threads:[~2016-10-21 14:57 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-21 11:58 [PATCH/RFC 0/5] cpu_relax: introduce yield, remove lowlatency Christian Borntraeger
2016-10-21 11:58 ` [PATCH 1/5] processor.h: introduce cpu_relax_yield Christian Borntraeger
2016-10-21 11:58 ` [PATCH 2/5] stop_machine: yield CPU during stop machine Christian Borntraeger
2016-10-21 12:05 ` Peter Zijlstra
2016-10-21 12:41 ` Juergen Gross
2016-10-22 0:06 ` Nicholas Piggin
2016-10-24 7:52 ` Christian Borntraeger
2016-10-24 8:47 ` Peter Zijlstra
2016-10-21 11:58 ` [PATCH 3/5] s390: make cpu_relax a barrier again Christian Borntraeger
2016-10-21 11:58 ` [PATCH 4/5] Remove cpu_relax_lowlatency users Christian Borntraeger
2016-10-21 11:58 ` [PATCH 5/5] remove cpu_relax_lowlatency Christian Borntraeger
2016-10-21 12:06 ` [PATCH/RFC 0/5] cpu_relax: introduce yield, remove lowlatency Peter Zijlstra
2016-10-21 14:57 ` David Miller [this message]
2016-10-21 15:08 ` Christian Borntraeger
2016-10-21 15:12 ` David Miller
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