Messages in this thread | | | Date | Wed, 20 Feb 2002 18:29:43 -0800 | From | Kimio Suganuma <> | Subject | Re: [Lse-tech] Re: [PATCH] O(1) scheduler set_cpus_allowed for non-current tasks |
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On Wed, 20 Feb 2002 18:04:49 -0800 Paul Jackson <pj@engr.sgi.com> wrote:
> On Wed, 20 Feb 2002, Kimio Suganuma wrote: > > > > CPU hotplug needs to change cpus_allowed in definite time. > > When a process is sleeping for 100000 seconds, how can we offline > > a CPU the process belongs? > > Good - I figured I'd hear from you on this - thanks. > > Are you thinking "definite time" on the order of a second? > I presume you don't require millisecond response time, and that > minute response time would be too slow, right?
Exactly.
> And just brainstorming ... if a process is sleeping for a long > time, and the last cpu it executed on is being taken offline, > what need is there to wake up the process? Let the process > stay asleep, and find it a new home when it wakes up for other > reasons.
In such the case, the waken up process's p->cpu must be changed by another process or in interrupt, not by itself. So, we cannot assume that p->cpu, or p->cpus_allowed, must be changed by itself, right?
> In other words, perhaps the goal of having the smallest, > simplest, least intrusive, most clearly correct code is more > important here than waking up a process just to tell it that > it's last cpu went offline.
Smallest, simplest and correct... I wish I could figure out such codes. :(
Regards, Kimi
-- Kimio Suganuma <k-suganuma@mvj.biglobe.ne.jp>
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