Messages in this thread | | | Subject | Re: [PATCH 1/1] hotplug cpu: migrate a task within its cpuset | From | Rusty Russell <> | Date | Sun, 26 Aug 2007 10:47:24 +1000 |
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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.
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