From: Rusty Russell <rusty@rustcorp.com.au>
To: ego@in.ibm.com
Cc: Oleg Nesterov <oleg@tv-sign.ru>,
Andrew Morton <akpm@linux-foundation.org>,
Cliff Wickman <cpw@sgi.com>,
mingo@elte.hu, vatsa@in.ibm.com, pj@sgi.com,
linux-kernel@vger.kernel.org, ntl@in.ibm.com,
Dipankar Sarma <dipankar@in.ibm.com>
Subject: Re: [PATCH 1/1] hotplug cpu: migrate a task within its cpuset
Date: Sun, 26 Aug 2007 10:47:24 +1000 [thread overview]
Message-ID: <1188089244.19877.3.camel@localhost.localdomain> (raw)
In-Reply-To: <20070826001625.GA17962@in.ibm.com>
On Sun, 2007-08-26 at 05:46 +0530, Gautham R Shenoy wrote:
> On Sat, Aug 25, 2007 at 01:47:40PM +0400, Oleg Nesterov wrote:
> > Before this patch, process leaves its ->cpuset and migrates to some "random"
> > any_online_cpu(). With this patch it stays within ->cpuset and migrates to
> > CPU 3.
>
> The decision to bind a task to a specific cpu, was taken by the userspace
> for a reason, which is _unknown_ to the kernel.
> So logically, shouldn't the userspace decide what should be
> the fate of those exclusive-affined tasks, whose cpu is about to go
> offline? After all, the reason to offline the cpu is, again, unknown to
> the kernel.
Userspace is not monolithic. If you refuse to take a CPU offline
because a task is affine, then any user can prevent a CPU from going
offline.
You could, perhaps, introduce a "gentle" offline which fails if process
affinity can no longer be met.
Rusty.
next prev parent reply other threads:[~2007-08-26 0:48 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-08-24 22:18 [PATCH 1/1] hotplug cpu: migrate a task within its cpuset Cliff Wickman
2007-08-24 22:54 ` Andrew Morton
2007-08-25 9:47 ` Oleg Nesterov
2007-08-26 0:16 ` Gautham R Shenoy
2007-08-26 0:47 ` Rusty Russell [this message]
2007-08-26 8:09 ` Andrew Morton
2007-08-27 7:01 ` Rusty Russell
2007-08-25 9:58 ` Oleg Nesterov
2007-08-25 11:18 ` Oleg Nesterov
-- strict thread matches above, loose matches on Subject: below --
2007-05-23 21:29 Oleg Nesterov
2007-05-23 22:56 ` Cliff Wickman
2007-05-23 23:32 ` Oleg Nesterov
2007-05-21 20:08 Cliff Wickman
2007-05-23 17:43 ` Andrew Morton
2007-05-24 7:56 ` Ingo Molnar
2007-05-29 19:32 ` Andrew Morton
2007-03-09 19:39 Cliff Wickman
2007-03-09 23:58 ` Nathan Lynch
2007-03-15 0:36 ` Robin Holt
2007-03-15 7:32 ` Nathan Lynch
2007-03-10 9:19 ` Ingo Molnar
2007-03-10 15:51 ` Nathan Lynch
2007-03-10 17:08 ` Ingo Molnar
2007-03-07 14:24 Cliff Wickman
2007-03-07 18:25 ` Randy Dunlap
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