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On Mon, Nov 06 2006, Brent Baccala wrote: > On Sun, 5 Nov 2006, Jens Axboe wrote: > > >On Fri, Nov 03 2006, Brent Baccala wrote: > >> > >>Does 7 microseconds seem a bit excessive for an io_submit (and a > >>gettimeofday)? > > > >I guess you mean miliseconds, not microseconds. 7 miliseconds seems way > >too long. I repeated your test here, and the 100 submits take 97000 > >microseconds here - or 97 miliseconds. So that's a little less than 1 > >msec per io_submit. Still pretty big. You can experiment with oprofile > >to profile where the kernel spends its time in that period. > > > >-- > >Jens Axboe > > > > Yes, of course, milliseconds. I have enough other problems with this > program (measured in minutes, and no mistake that) that I doubt I'll > be profiling the kernel any time soon, but thank you for your help. > > More than anything else, you've made me understand that I can't just > fire off a bunch of async requests like I'm tossing peanuts across the > table. I've really got to pay attention to what's in that kernel > queue and how it gets managed. Yeah, I'm afraid so. We really should be returning EAGAIN or something like that for the congested condition, though. -- Jens Axboe - 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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