Messages in this thread Patch in this message | | | Date | Thu, 21 Jun 2007 23:02:32 +0530 | From | Srivatsa Vaddagiri <> | Subject | Re: cpuset attach_task to touch per-cpu kernel threads? |
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On Thu, Jun 21, 2007 at 10:07:12AM -0700, Paul Jackson wrote: > Ingo, responding to Srivatsa: > > > Or maybe allow movement if it > > > doesn't result in changing kernel-threads's cpu affinity. > > > > yeah, i'd agree .. > > Good point. I'd agree too.
Yeah .."allow movement if it doesn't result in changing kernel-threads's cpu affinity" sounds good, except it is hard to implement in cpuset's context I think. For ex: we now have to take additional steps when changing 'cpus_allowed' of a cpuset such that it doesn't violate any cpu affinity of kernel threads bound to the cpuset. That itself makes the implementation complex I think.
How about a simpler patch which bans movement of kernel threads from its home cpuset (i.e top cpuset)?
Index: current/kernel/cpuset.c =================================================================== --- current.orig/kernel/cpuset.c 2007-06-21 19:42:18.000000000 +0530 +++ current/kernel/cpuset.c 2007-06-21 22:24:38.000000000 +0530 @@ -881,6 +881,10 @@ if (cpus_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)) return -ENOSPC; + /* Don't allow kernel threads to be moved */ + if (!tsk->mm) + return -EINVAL; + return security_task_setscheduler(tsk, 0, NULL); } This probably catches exiting user-space tasks also (whose ->mm pointer is null). Hmm ..there should be a better check for kernel threads.
-- Regards, vatsa - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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