Messages in this thread | | | Subject | Re: [patch] voluntary-preempt-2.6.8-rc2-L2, preemptable hardirqs | From | Lee Revell <> | Date | Thu, 29 Jul 2004 15:43:09 -0400 |
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On Thu, 2004-07-29 at 14:04, Ingo Molnar wrote: > * Lee Revell <rlrevell@joe-job.com> wrote: > > > Here are some more results. I am up to 56 million interrupts and I > > have yet to trigger a latency higher than 46 usecs. It looks like > > this is a hard upper limit. > > nice - what is the average (and minimum?) latency reported by jackd? > I'd say 46 usecs on a 600 MHz box is quite close to what it takes to > handle an interrupt and schedule to the cache-cold jackd task. It should > definitely be well below the latency required for jackd to do its job > reliably.
Yes, I am quite impressed with these results. The jitter is about 5-10% of the total available time at the very lowest latency settings. This is an order of magnitude better than 2.4 + ll. It went as high as 50 usecs, but this took about 100 million interrupts. I have not hacked jackd yet to keep track of the average and minimum value, but eyeballing it I would say 7-8 usecs is the minimum and 25-30 the average. The distribution seems very normal.
I am going to try making the RTC irq non-redirectable as well, as I got a few 'rtc: lost some interrupts at 1024 Hz' messages, and the RTC is important for MIDI timing.
Other than the few outliers I reported earlier, this is very close to being ready for general pro audio use. I did notice that the msync() XRUN can be reliably reproduced by 'apt-get update && apt-get upgrade'.
I think I can speak on behalf of all Linux audio users when I say: thanks a million, to all kernel developers.
Lee
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