From linux-kernel Sat Aug 21 09:10:36 2004 From: Ingo Molnar Date: Sat, 21 Aug 2004 09:10:36 +0000 To: linux-kernel Subject: Re: [patch] voluntary-preempt-2.6.8.1-P6 Message-Id: <20040821091036.GA25864 () elte ! hu> X-MARC-Message: https://marc.info/?l=linux-kernel&m=109307966027284 * Lee Revell wrote: > Also I have noticed a pattern with the XFree86 schedule() latencies, > they all have a section like this: > > 04000002 0.003ms (+0.000ms): effective_prio (recalc_task_prio) > 04000002 0.003ms (+0.000ms): enqueue_task (schedule) > 00000002 0.006ms (+0.003ms): __switch_to (schedule) > 00000002 0.088ms (+0.082ms): finish_task_switch (schedule) > 00010002 0.090ms (+0.001ms): do_IRQ (finish_task_switch) > I presume the 04000002 -> 00000002 is some interrupt being unmasked > (or interrupts being globally enabled), then there's a 60-80 usec > latency in schedule(). 0x04000000 is PREEMPT_ACTIVE - which is just a bit we set to make sure we dont try to preempt recursively. but the XFree86 latency is interesting indeed. It could be the effect of the now-enlarged ioperm() bitmap! 80 usecs is excessive. Ingo - 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/