linux-kernel - Re: Rescheduling interrupts

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]

Message-ID: <20080122192744.GB3218@elte.hu>
Date:	Tue, 22 Jan 2008 20:27:44 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Matt Mackall <mpm@...enic.com>
Cc:	S.Çağlar Onur <caglar@...dus.org.tr>,
	LKML <linux-kernel@...r.kernel.org>,
	Arjan van de Ven <arjan@...ux.intel.com>
Subject: Re: Rescheduling interrupts


* Matt Mackall <mpm@...enic.com> wrote:

> > amarokapp does wake up threads every 20 microseconds - that could 
> > explain it. It's probably Xorg running on one core, amarokapp on the 
> > other core. That's already 100 reschedules/sec.
> 
> That suggests we want an "anti-load-balancing" heuristic when CPU 
> usage is very low. Migrating everything onto one core when we're close 
> to idle will save power and probably reduce latencies.

that would probably be the case if it's multiple sockets - but for 
multiple cores exactly the opposite is true: the sooner _both_ cores 
finish processing, the deeper power use the CPU can reach. So effective 
and immediate spreading of workloads amongst multiple cores - especially 
with shared L2 caches where the cost of migration is low, helps power 
consumption. (and it obviously helps latencies and bandwith)

	Ingo
--
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/