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Date: Thu, 12 Nov 2009 12:34:29 +0100 From: Ingo Molnar <mingo@...e.hu> To: Peter Zijlstra <peterz@...radead.org> Cc: Mike Galbraith <efault@....de>, LKML <linux-kernel@...r.kernel.org> Subject: Re: [patch] sched: fix/add missing update_rq_clock() calls * Peter Zijlstra <peterz@...radead.org> wrote: > On Thu, 2009-11-12 at 12:27 +0100, Ingo Molnar wrote: > > * Peter Zijlstra <peterz@...radead.org> wrote: > > > > > On Thu, 2009-11-12 at 11:07 +0100, Mike Galbraith wrote: > > > > sched: fix/add missing update_rq_clock() calls. > > > > > > > > kthread_bind(), migrate_task() and sched_fork were missing updates, and > > > > try_to_wake_up() was updating after having already used the stale clock. > > > > > > > > > I'm almost at the point where I think we should ditch rq->clock > > > alltogether and simply call cpu_clock() directly when we need it. This > > > trying to optimize and avoid calling it game has brought way too many > > > head-aches. > > > > It's not just about optimization - it's also accounting precision - we > > want to handle the full act of schedule() at a single timestamp - not a > > series of timestamps. > > > > But ... we can get rid of it if it can be done sanely. > > Ah, good point, hard to do for the migration paths though. yes, migration is always the odd one out anyway, unless the hardware does cross-CPU-synchronous timestamps. Ingo -- 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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