linux-kernel - Re: sched: Avoid SMT siblings in select_idle

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 23 Feb 2012 17:02:24 +0530
From:	Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Mike Galbraith <efault@....de>,
	Peter Zijlstra <peterz@...radead.org>,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Paul Turner <pjt@...gle.com>
Subject: Re: sched: Avoid SMT siblings in select_idle_sibling() if possible

* Ingo Molnar <mingo@...e.hu> [2012-02-23 12:26:50]:

> pro perf tip of the day: did you know that it's possible to run:
> 
>   perf stat --repeat 10 --null perf bench sched pipe

Ah yes ..had forgotten that! What is the recommended # of iterations 
to run?

> and get meaningful, normalized stddev calculations for free:
> 
>        5.486491487 seconds time elapsed                                          ( +-  5.50% )
> 
> the percentage at the end shows the level of standard deviation.
> 
> You can add "--sync" as well, which will cause perf stat to call 
> sync() - this gives extra stability of individual iterations and 
> makes sure all IO cost is accounted to the right run.

Ok ..thanks for the 'pro' tip!! Will use it in my subsequent runs!

- vatsa

--
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/