linux-kernel - Re: [PATCH 0/3] cpu: idle state framework for offline CPUs.

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: <20090806015855.GA20596@sli10-desk.sh.intel.com>
Date:	Thu, 6 Aug 2009 09:58:55 +0800
From:	Shaohua Li <shaohua.li@...el.com>
To:	Gautham R Shenoy <ego@...ibm.com>
Cc:	Joel Schopp <jschopp@...tin.ibm.com>,
	"Brown, Len" <len.brown@...el.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Balbir Singh <balbir@...ibm.com>,
	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Ingo Molnar <mingo@...e.hu>,
	Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
	Dipankar Sarma <dipankar@...ibm.com>,
	"Darrick J. Wong" <djwong@...ibm.com>,
	"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/3] cpu: idle state framework for offline CPUs.

Hi,

On Wed, Aug 05, 2009 at 10:25:53PM +0800, Gautham R Shenoy wrote:
> In this patch-series, we propose to extend the CPU-Hotplug infrastructure
> and allow the system administrator to choose the desired state the CPU should
> go to when it is offlined. We think this approach addresses the concerns about
> determinism as well as transparency, since CPU-Hotplug already provides
> notification mechanism which the userspace can listen to for any change
> in the configuration and correspondingly readjust any previously set
> cpu-affinities.
Peter dislikes any approach (including cpuhotplug) which breaks userspace policy,
even userspace can get a notification.

> Also, approaches such as [1] can make use of this
> extended infrastructure instead of putting the CPU to an arbitrary C-state
> when it is offlined, thereby providing the system administrator a rope to hang
> himself with should he feel the need to do so.
I didn't see the reason why administrator needs to know which state offline cpu
should stay. Don't know about powerpc side, but in x86 side, it appears deepest
C-state is already preferred.

Thanks,
Shaohua
--
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/