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Message-ID: <53CEBD2F.2040705@hp.com> Date: Tue, 22 Jul 2014 15:36:15 -0400 From: Waiman Long <waiman.long@...com> To: Ingo Molnar <mingo@...nel.org> CC: Thomas Gleixner <tglx@...utronix.de>, Peter Zijlstra <peterz@...radead.org>, Darren Hart <dvhart@...ux.intel.com>, Davidlohr Bueso <davidlohr@...com>, Heiko Carstens <heiko.carstens@...ibm.com>, linux-kernel@...r.kernel.org, linux-api@...r.kernel.org, linux-doc@...r.kernel.org, Jason Low <jason.low2@...com>, Scott J Norton <scott.norton@...com> Subject: Re: [RFC PATCH 0/5] futex: introduce an optimistic spinning futex On 07/21/2014 05:18 PM, Ingo Molnar wrote: > * Waiman Long<Waiman.Long@...com> wrote: > >> Testing done on a 4-socket Westmere-EX boxes with 40 cores (HT off) >> showed the following performance data (average kops/s) with various >> load factor (number of pause instructions) used in the critical >> section using an userspace mutex microbenchmark. >> >> Threads Load Waiting Futex Spinning Futex %Change >> ------- ---- ------------- -------------- ------- >> 256 1 6894 8883 +29% >> 256 10 3656 4912 +34% >> 256 50 1332 4358 +227% >> 256 100 792 2753 +248% >> 10 1 6382 4838 -24% >> 10 10 3614 4748 +31% >> 10 50 1319 3900 +196% >> 10 100 782 2459 +214% >> 2 1 7905 7194 -9.0% >> 2 10 4556 4717 +3.5% >> 2 50 2191 4167 +90% >> 2 100 1767 2407 +36% > So the numbers look interesting - but it would be _really_ important > to provide noise/sttdev figures in a sixth column as well (denoted in > percentage units, not in benchmark units), so that we know how > significant a particular speedup (or slowdown) is. > > Thanks, > > Ingo The performance can varies quite a bit depending on what other processes are running at the test execution time. I will include stddev data in the next iteration of the patch. -Longman -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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