From: Andi Kleen <ak@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
"H. Peter Anvin" <hpa@zytor.com>,
Linux-Next Mailing List <linux-next@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: linux-next: manual merge of the akpm tree with the tip tree
Date: Fri, 31 Mar 2017 09:02:42 -0700 [thread overview]
Message-ID: <20170331160242.GF4543@tassilo.jf.intel.com> (raw)
In-Reply-To: <20170331144546.4bi6lnrcx4t6cyze@hirez.programming.kicks-ass.net>
On Fri, Mar 31, 2017 at 04:45:46PM +0200, Peter Zijlstra wrote:
> On Fri, Mar 31, 2017 at 06:54:48AM -0700, Andi Kleen wrote:
> > > Argh!
> > >
> > > Andrew, please drop that patch. And the x86 out-of-line of __atomic_add_unless().
> >
> > Why dropping the second? Do you have something better?
>
> The try_cmpxchg() patches save about half the text, and do not have the
> out-of-line penalty as shown here:
>
> https://lkml.kernel.org/r/20170322165144.dtidvvbxey7w5pbd@hirez.programming.kicks-ass.net
Where is the source for the benchmark?
Based on the description it sounds like it's testing atomic_inc(), which my patches
don't change.
BTW testing such things in tight loops is bad practice. If you run
them back to back the CPU pipeline has to do much more serialization,
which is usually not realistic and drastically overestimates
the overhead.
A better practice is to run some real workload. If you want to see
cycle counts you can look at LBR cycles, or PT cycles from sampling or tracing.
> > On the first there were no 0day regressions, so at least basic performance
> > checking has been done.
>
> The first is superseded by much better patches in the scheduler tree.
Which patches exactly? The new patches shrink the text too?
-Andi
next prev parent reply other threads:[~2017-03-31 16:02 UTC|newest]
Thread overview: 85+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-31 5:44 linux-next: manual merge of the akpm tree with the tip tree Stephen Rothwell
2017-03-31 6:42 ` Peter Zijlstra
2017-03-31 13:54 ` Andi Kleen
2017-03-31 14:45 ` Peter Zijlstra
2017-03-31 16:02 ` Andi Kleen [this message]
2017-03-31 17:48 ` Peter Zijlstra
-- strict thread matches above, loose matches on Subject: below --
2020-05-29 10:57 Stephen Rothwell
2020-05-29 10:49 Stephen Rothwell
2020-01-22 6:37 Stephen Rothwell
2019-02-13 6:49 Stephen Rothwell
2019-02-13 19:59 ` Andrew Morton
2018-01-09 5:02 Stephen Rothwell
2018-01-09 10:36 ` Andy Shevchenko
2017-10-16 18:48 Mark Brown
2017-10-16 20:01 ` Mark Brown
2017-04-12 7:08 Stephen Rothwell
2017-03-24 5:40 Stephen Rothwell
2017-03-24 8:05 ` Peter Zijlstra
2016-03-10 5:28 Stephen Rothwell
2016-03-10 8:00 ` Ingo Molnar
2016-03-10 20:38 ` Andrew Morton
2016-02-09 4:50 Stephen Rothwell
2016-02-09 14:04 ` Matt Fleming
2016-02-09 14:07 ` Ingo Molnar
2015-06-09 14:12 Stephen Rothwell
2015-04-08 8:49 Stephen Rothwell
2015-04-08 15:13 ` Ingo Molnar
2015-04-08 20:46 ` Andrew Morton
2015-04-08 21:57 ` Stephen Rothwell
2014-03-21 6:45 Stephen Rothwell
2014-01-13 6:17 Stephen Rothwell
2013-04-23 7:17 Stephen Rothwell
2013-02-14 4:33 Stephen Rothwell
2013-02-14 4:25 Stephen Rothwell
2013-02-14 4:34 ` H. Peter Anvin
2013-02-04 7:00 Stephen Rothwell
2013-01-28 12:29 Stephen Rothwell
2012-12-10 8:29 Stephen Rothwell
2012-12-10 10:46 ` Ingo Molnar
2012-12-10 8:25 Stephen Rothwell
2012-12-10 8:20 Stephen Rothwell
2012-12-10 8:11 Stephen Rothwell
2012-12-10 8:01 Stephen Rothwell
2012-12-10 11:13 ` Will Deacon
2012-12-10 7:47 Stephen Rothwell
2012-11-15 6:32 Stephen Rothwell
2012-10-01 14:22 Stephen Rothwell
2012-09-27 7:15 Stephen Rothwell
2012-09-27 7:10 Stephen Rothwell
2012-09-27 7:04 Stephen Rothwell
2012-09-27 6:57 Stephen Rothwell
2012-09-27 6:49 Stephen Rothwell
2012-07-27 3:50 Stephen Rothwell
2012-07-25 4:08 Stephen Rothwell
2012-07-25 7:10 ` Ingo Molnar
2012-07-25 7:35 ` Johannes Weiner
2012-07-25 18:57 ` Andrew Morton
2012-07-25 19:03 ` Ingo Molnar
2012-07-25 19:26 ` Andrew Morton
2012-07-26 7:51 ` Ingo Molnar
2012-07-26 18:05 ` Andrew Morton
2012-07-25 19:20 ` Johannes Weiner
2012-07-26 7:03 ` Stephen Rothwell
2012-05-21 8:29 Stephen Rothwell
2012-05-21 8:04 Stephen Rothwell
2012-05-21 7:59 Stephen Rothwell
2012-03-27 4:57 Stephen Rothwell
2012-03-26 4:01 Stephen Rothwell
2012-03-26 5:20 ` Alex Shi
2012-03-08 6:32 Stephen Rothwell
2012-03-08 6:28 Stephen Rothwell
2012-02-29 6:27 Stephen Rothwell
2012-02-28 4:52 Stephen Rothwell
2012-02-27 5:53 Stephen Rothwell
2012-02-27 5:57 ` Cyrill Gorcunov
2012-02-27 6:02 ` H. Peter Anvin
2012-02-27 6:05 ` Cyrill Gorcunov
2012-02-27 6:01 ` H. Peter Anvin
2012-02-27 6:19 ` Stephen Rothwell
2012-02-27 5:44 Stephen Rothwell
2012-02-27 5:33 Stephen Rothwell
2012-02-27 5:23 Stephen Rothwell
2012-02-27 5:16 Stephen Rothwell
2011-12-06 4:04 Stephen Rothwell
2011-09-27 7:13 Stephen Rothwell
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