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Date: Fri, 27 Jun 2008 13:48:16 -0500 From: Robin Holt <holt@....com> To: xialiang <xiaiaxaxi@...u.edu.cn> Cc: Bart Van Assche <bart.vanassche@...il.com>, linux-kernel@...r.kernel.org Subject: Re: How can I migrate a currently running task? On Fri, Jun 27, 2008 at 09:38:05PM +0800, xialiang wrote: > Quoting Bart Van Assche <bart.vanassche@...il.com>: > >> On Fri, Jun 27, 2008 at 3:17 PM, 夏亮 <xiaiaxaxi@...u.edu.cn> wrote: >>> I am working on Intel Duo Core with Linux OS 2.6.21, and I'd like to >>> migrate task from one cpu to another cpu. >>> In SMP systems, load_balance() function uses move_tasks() to move processes >>> from source runqueue to local runqueue, but it does not move a currently >>> running task. If I want to migrate a currently running task from source >>> runqueue to local runqueue, how can I do? Any suggestion is preferred. >> >> Are you familiar with the glibc pthread_setaffinity_np() function >> and/or the sched_setaffinity() system call ? >> >> Bart. >> > > Yes. I know sched_setaffinity(), it sets cpu_mask of a task. I want to > use it in a timer interrupt( scheduler_tick() ), can I? Don't use it from a timer handler. You can use migrate_task() to move the task, but your email from a couple days ago said you wanted to move the task at the head of the runqueue due to cpu heat or something like that. That is a very imprecise way to move the task as any unfortunate task that happens to be running when the timer tick occurs could get migrated, not the one generating the work. I think you really want to look at the other areas of the kernel which do stuff like throttling the cpu. Just moving a task off the cpu does not prevent it from being used for another compute intesive load. You could take the cpu offline. I guess to do that, I would use schedule_work() or kthread_create() to get out of the timer context and into a regular thread context then take the cpu offline from there. Good Luck, Robin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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