linux-kernel - Re: [RFC][PATCH 0/9] sched: Power scheduler design proposal

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:	Mon, 15 Jul 2013 10:05:15 +0800
From:	Alex Shi <alex.shi@...el.com>
To:	Arjan van de Ven <arjan@...ux.intel.com>
CC:	Peter Zijlstra <peterz@...radead.org>,
	Morten Rasmussen <morten.rasmussen@....com>, mingo@...nel.org,
	vincent.guittot@...aro.org, preeti@...ux.vnet.ibm.com,
	efault@....de, pjt@...gle.com, len.brown@...el.com, corbet@....net,
	akpm@...ux-foundation.org, torvalds@...ux-foundation.org,
	tglx@...utronix.de, catalin.marinas@....com,
	linux-kernel@...r.kernel.org, linaro-kernel@...ts.linaro.org
Subject: Re: [RFC][PATCH 0/9] sched: Power scheduler design proposal

On 07/14/2013 12:14 AM, Arjan van de Ven wrote:
> 
> 
> on thinking more about the short running task thing; there is an
> optimization we currently don't do,
> mostly for hyperthreading. (and HT is just one out of a set of cases
> with similar power behavior)
> If we know a task runs briefly AND is not performance critical, it's
> much much better to place it on
> a hyperthreading buddy of an already busy core than it is to place it on
> an empty core (or to delay it).
> Yes a HT pair isn't the same performance as a full core, but in terms of
> power the 2nd half of a HT pair
> is nearly free... so if there's a task that's not performance sensitive
> (and won't disturb the other task too much,
> e.g. runs briefly enough)... it's better to pack onto a core than to
> spread.
> you can generalize this to a class of systems where adding work to a
> core (read: group of cpus that share resources)
> is significantly cheaper than running on a full empty core.

Right!
That is one of purpose that my old power sheduling's wanna do:
https://lkml.org/lkml/2013/4/3/747
Vincent's patchset also target at this.

-- 
Thanks
    Alex
--
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/