Messages in this thread |  | | | Date | Mon, 06 Sep 2004 22:17:22 -0500 | | From | "K.R. Foley" <> | | Subject | Re: [patch] voluntary-preempt-2.6.9-rc1-bk12-R5 |
| |
Lee Revell wrote: > On Mon, 2004-09-06 at 02:30, Ingo Molnar wrote: > >>* Lee Revell <rlrevell@joe-job.com> wrote: >> >> >>>http://krustophenia.net/testresults.php?dataset=2.6.9-rc1-R0#/var/www/2.6.9-rc1-R0/foo.hist >>> >>>I find the two smaller spikes to either side of the central spike >>>really odd. These showed up in my jackd tests too, I had attributed >>>them to some measurement artifact, but they seem real. Maybe a >>>rounding bug, or some kind of weird cache effect? >> >>interesting - the histograms are pretty symmetric around the center. >>E.g. the exponential foo.hist2 diagram is way too symmetric around 50 >>usecs! What precisely is being measured? >> > > > Here's the program. It does mlockall(), acquires realtime scheduling, > then sets up a 2048 Hz stream of interupts from the RTC and measures the > delay. It's quite possible there's a bug, the amlat program did not > seem to work, something must have changed with the RTC from 2.4 to 2.6. >
Actually the amlat program works fine for applying real-time scheduling pressure. I believe it just doesn't do any real latency measuring without the hooks provided by Andrew's rtc-debug patch.
kr - 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/
|  |