From: Ingo Molnar <mingo@kernel.org>
To: Mel Gorman <mgorman@suse.de>
Cc: Alex Shi <alex.shi@linaro.org>, H Peter Anvin <hpa@zytor.com>,
Linux-X86 <x86@kernel.org>, Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC PATCH 0/3] Fix ebizzy performance regression on IvyBridge due to X86 TLB range flush
Date: Fri, 13 Dec 2013 14:35:17 +0100 [thread overview]
Message-ID: <20131213133517.GA11176@gmail.com> (raw)
In-Reply-To: <20131212144029.GI11295@suse.de>
* Mel Gorman <mgorman@suse.de> wrote:
> > [...]
> >
> > stddev appears to be rather large especially around a client count
> > of 7-8. It will be difficult to fine-tune the TLB range flush
> > constants if noise is too large.
>
> The number of iterations were very low to have high confidence of
> the figures. The high standard deviation for 5 clients was a single
> large outlier. It potentially could be stabilised to some extent by
> bumping up the number of iterations a lot and using percentiles
> instead of means.
Fair enough - and you were bisecting so length of runtime and
confidence of detection were obviously the primary concerns.
> I'm a bit wary of optimising the TLB flush ranges based on the
> benchmark even if we stabilised the figures. [...]
Absolutely - but they do appear to be pretty 'adversarial' to the TLB
optimization, with a measurable slowdown in a pretty complex,
real-life workload pattern.
So future tuning efforts will have to take such workloads into effect
as well, to make sure we don't regress again.
Thanks,
Ingo
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prev parent reply other threads:[~2013-12-13 13:35 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-12 11:55 [RFC PATCH 0/3] Fix ebizzy performance regression on IvyBridge due to X86 TLB range flush Mel Gorman
2013-12-12 11:55 ` [PATCH 1/3] x86: mm: Clean up inconsistencies when flushing TLB ranges Mel Gorman
2013-12-12 13:59 ` Alex Shi
2013-12-12 23:53 ` Mel Gorman
2013-12-12 11:55 ` [PATCH 2/3] x86: mm: Change tlb_flushall_shift for IvyBridge Mel Gorman
2013-12-12 13:13 ` Ingo Molnar
2013-12-12 13:38 ` Alex Shi
2013-12-12 14:11 ` Ingo Molnar
2013-12-13 1:02 ` Alex Shi
2013-12-13 2:11 ` Alex Shi
2013-12-13 13:43 ` Ingo Molnar
2013-12-14 11:01 ` Alex Shi
2013-12-14 14:19 ` Peter Zijlstra
2013-12-14 14:27 ` Peter Zijlstra
2013-12-16 13:59 ` Ingo Molnar
2013-12-17 11:59 ` Alex Shi
2013-12-17 13:14 ` Ingo Molnar
2013-12-16 8:26 ` Alex Shi
2013-12-16 10:06 ` Peter Zijlstra
2013-12-12 13:45 ` Alex Shi
2013-12-12 11:55 ` [PATCH 3/3] x86: mm: Account for the of CPUs that must be flushed during a TLB range flush Mel Gorman
2013-12-12 13:41 ` Alex Shi
2013-12-12 13:01 ` [RFC PATCH 0/3] Fix ebizzy performance regression on IvyBridge due to X86 " Ingo Molnar
2013-12-12 14:40 ` Mel Gorman
2013-12-13 13:35 ` Ingo Molnar [this message]
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