Messages in this thread | | | Date | Thu, 12 Sep 2013 11:51:07 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [RFC] Restrict kernel spawning of threads to a specified set of cpus. |
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On Thu, Sep 12, 2013 at 08:35:05PM +0200, Frederic Weisbecker wrote: > On Thu, Sep 12, 2013 at 08:39:22AM -0700, Paul E. McKenney wrote: > > On Thu, Sep 12, 2013 at 05:11:04PM +0200, Frederic Weisbecker wrote: > > > On Thu, Sep 12, 2013 at 02:52:56PM +0000, Christoph Lameter wrote: > > > > On Thu, 12 Sep 2013, Frederic Weisbecker wrote: > > > > > > > > > > > Ok but you can change the affinity of a kthread from userspace, as > > > > > > > long as you define a cpu set that is among that kthread's cpus allowed. > > > > > > > > > > > > Ok but at that point kthread has already spawned a lot of kernel threads. > > > > > > > > > > > > The same is true for init and kmod. > > > > > > > > > > > > > > > > Ok but then we just need to set the affinity of all these kthreads. > > > > > A simple lookup on /proc/[0-9]+/ should do the trick. > > > > > > > > Yea but the kernel option makes it easy. No extras needed. Kernel brings > > > > it up user space cleanly configured and ready to go. > > > > > > Ok but really that's just two lines of bash. I really wish we don't complicate > > > core kernel code for that. > > > > OK, I will bite... How do you handle the case where you have collected > > all the kthreads, one of the kthreads spawns another kthread, then you > > set affinity on the collected kthreads, which does not include the newly > > spawned one? > > Just offline the CPUs you want to isolate, affine your kthreads and re-online > the CPUs. > > If you're lucky enough to have 1024 CPUs, a winter night should be enough ;-)
Running at RT prio 99 to reduce the probability of respawns? ;-)
Thanx, Paul
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