Messages in this thread | | | Date | Mon, 6 Dec 1999 19:01:35 +0100 (CET) | From | Ingo Molnar <> | Subject | Re: setitimer lowlatency-2.2.13-A1 questions |
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On Mon, 6 Dec 1999, William Montgomery wrote:
> I tried using setitimer as a scheduling source for lowlatency testing > with generally good results. I left my test running over the weekend > and found some large latencies had occurred. It appears that since > the signal generation occurs in timer_bh, it is possible for a user > task to run between when the timer_interrupt occurs and when timer_bh > runs (~2msec in my case).
that should not be possible (except on SMP where there might be a window). You are not running SMP, right? The TIMER_BH is run right when the IRQ handler returns to non-irq context (which might be user-space or kernel space), so it's not possible to 'lose' a TIMER_BH event due to some task running. BHs might get delayed due to interrupts though, so you might want to profile how long various interrupt sources execute.
-- mingo
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