From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>,
linux-kernel@vger.kernel.org,
Corey Ashford <cjashfor@linux.vnet.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 2/2] perf_counter: optimize context switch between identical inherited contexts
Date: Fri, 22 May 2009 11:22:09 +0200 [thread overview]
Message-ID: <1242984129.26820.627.camel@twins> (raw)
In-Reply-To: <18966.10666.517218.332164@cargo.ozlabs.ibm.com>
On Fri, 2009-05-22 at 14:27 +1000, Paul Mackerras wrote:
>
> -----Unmodified----- With this patch series
> Counters: none 2 HW 4H+4S none 2 HW 4H+4S
>
> 2 processes:
> Average 3.44 6.45 11.24 3.12 3.39 3.60
> St dev 0.04 0.04 0.13 0.05 0.17 0.19
>
> 8 processes:
> Average 6.45 8.79 14.00 5.57 6.23 7.57
> St dev 1.27 1.04 0.88 1.42 1.46 1.42
>
> 32 processes:
> Average 5.56 8.43 13.78 5.28 5.55 7.15
> St dev 0.41 0.47 0.53 0.54 0.57 0.81
Any clues as to why the time is still dependent on the number of
counters in the context? The approach seems to be O(1) in that it
does a simple counter context swap on sched_out and nothing on sched_in.
next prev parent reply other threads:[~2009-05-22 9:22 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-22 4:17 [PATCH 1/2] perf_counter: dynamically allocate tasks' perf_counter_context struct [v2] Paul Mackerras
2009-05-22 4:27 ` [PATCH 2/2] perf_counter: optimize context switch between identical inherited contexts Paul Mackerras
2009-05-22 8:16 ` Peter Zijlstra
2009-05-22 9:56 ` Paul Mackerras
2009-05-22 10:08 ` Peter Zijlstra
2009-05-23 12:38 ` Ingo Molnar
2009-05-23 13:06 ` Peter Zijlstra
2009-05-24 23:55 ` Paul Mackerras
2009-05-22 8:32 ` Peter Zijlstra
2009-05-22 8:57 ` Ingo Molnar
2009-05-22 9:02 ` Peter Zijlstra
2009-05-22 10:14 ` Ingo Molnar
2009-05-22 9:29 ` Paul Mackerras
2009-05-22 9:22 ` Peter Zijlstra [this message]
2009-05-22 9:42 ` Peter Zijlstra
2009-05-22 10:07 ` Paul Mackerras
2009-05-22 10:05 ` Paul Mackerras
2009-05-22 10:11 ` Ingo Molnar
2009-05-22 10:27 ` [tip:perfcounters/core] perf_counter: Optimize " tip-bot for Paul Mackerras
2009-05-24 11:33 ` Ingo Molnar
2009-05-25 6:18 ` Paul Mackerras
2009-05-25 6:54 ` Ingo Molnar
2009-05-22 10:36 ` [tip:perfcounters/core] perf_counter: fix !PERF_COUNTERS build failure tip-bot for Ingo Molnar
2009-05-22 13:46 ` [PATCH 2/2] perf_counter: optimize context switch between identical inherited contexts Peter Zijlstra
2009-05-25 0:15 ` Paul Mackerras
2009-05-25 10:38 ` Peter Zijlstra
2009-05-25 10:50 ` Peter Zijlstra
2009-05-25 11:06 ` Paul Mackerras
2009-05-25 11:27 ` Peter Zijlstra
2009-05-22 8:06 ` [PATCH 1/2] perf_counter: dynamically allocate tasks' perf_counter_context struct [v2] Peter Zijlstra
2009-05-22 9:30 ` Paul Mackerras
2009-05-22 10:27 ` [tip:perfcounters/core] perf_counter: Dynamically allocate tasks' perf_counter_context struct tip-bot for Paul Mackerras
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1242984129.26820.627.camel@twins \
--to=a.p.zijlstra@chello.nl \
--cc=cjashfor@linux.vnet.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=paulus@samba.org \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox