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From: Eliezer Tamir <eliezer.tamir@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>,
	lenb@kernel.org, rjw@rjwysocki.net,
	David Miller <davem@davemloft.net>,
	rui.zhang@intel.com, jacob.jun.pan@linux.intel.com,
	Mike Galbraith <bitbucket@online.de>,
	Ingo Molnar <mingo@kernel.org>,
	hpa@zytor.com, Thomas Gleixner <tglx@linutronix.de>,
	linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
Subject: Re: [PATCH 7/8] sched, net: Fixup busy_loop_us_clock()
Date: Fri, 29 Nov 2013 15:52:10 +0200	[thread overview]
Message-ID: <52989C0A.7000309@linux.intel.com> (raw)
In-Reply-To: <20131128174001.GH10022@twins.programming.kicks-ass.net>

On 28/11/2013 19:40, Peter Zijlstra wrote:
> On Thu, Nov 28, 2013 at 06:49:00PM +0200, Eliezer Tamir wrote:
>> I have tested this patch and I see a performance regression of about
>> 1.5%.
> 
> Cute, can you qualify your metric? Since this is a poll loop the only
> metric that would be interesting is the response latency. Is that what's
> increased by 1.5%? Also, what's the standard deviation of your result?

Sorry, I should have been more specific.

I use netperf tcp_rr, with all settings except the time (30s) on their
defaults. The setup is exactly the same as in the commit message of the
original patch set.

I get 91.5 KRR/s vs. 90.0 KRR/s.

Unfortunately you need two machines, both of which need NICs that have
driver support for busy poll. currently AFAIK bnx2x, ixgbe, mlx4 and
myri10ge are the only ones, but it's not that hard to add to most NAPI
based drivers.

I will try to test your latest patches and hopefully also get some perf
numbers on Sunday.

Thanks,
Eliezer

  parent reply	other threads:[~2013-11-29 13:52 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-11-26 15:57 [PATCH 0/8] Cure faux idle wreckage Peter Zijlstra
2013-11-26 15:57 ` [PATCH 1/8] x86, acpi, idle: Restructure the mwait idle routines Peter Zijlstra
2013-11-26 15:57 ` [PATCH 2/8] sched, preempt: Fixup missed PREEMPT_NEED_RESCHED folding Peter Zijlstra
2013-11-26 15:57 ` [PATCH 3/8] idle, thermal, acpi: Remove home grown idle implementations Peter Zijlstra
2013-11-26 15:57 ` [PATCH 4/8] preempt, locking: Rework local_bh_{dis,en}able() Peter Zijlstra
2013-11-26 15:57 ` [PATCH 5/8] locking: Optimize lock_bh functions Peter Zijlstra
2013-11-26 15:57 ` [PATCH 6/8] sched, net: Clean up preempt_enable_no_resched() abuse Peter Zijlstra
2013-11-26 15:57 ` [PATCH 7/8] sched, net: Fixup busy_loop_us_clock() Peter Zijlstra
2013-11-28 16:49   ` Eliezer Tamir
2013-11-28 17:40     ` Peter Zijlstra
2013-11-28 18:50       ` Peter Zijlstra
2013-11-29 13:52       ` Eliezer Tamir [this message]
2013-11-26 15:57 ` [PATCH 8/8] preempt: Take away preempt_enable_no_resched() from modules Peter Zijlstra
2013-11-26 23:23 ` [PATCH 0/8] Cure faux idle wreckage Jacob Pan

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