Messages in this thread | | | Subject | Re: [patch] voluntary-preempt-2.6.8-rc2-L2, preemptable hardirqs | From | Lee Revell <> | Date | Wed, 28 Jul 2004 21:56:47 -0400 |
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On Wed, 2004-07-28 at 21:08, Lee Revell wrote: > On Wed, 2004-07-28 at 17:50, Lee Revell wrote: > > On Wed, 2004-07-28 at 01:05, Ingo Molnar wrote: > > > * Lee Revell <rlrevell@joe-job.com> wrote: > > > if your soundcard doesnt share the irq line with any other 'heavy' > > > interrupt then you can make the irq 'direct' via a simple change to > > > arch/i386/kernel/irq.c, change this line from: > > > > > > #define redirectable_irq(irq) ((irq) != 0) > > > > > > to: > > > > > > #define redirectable_irq(irq) (((irq) != 0) && ((irq) != 10)) > > > > > > (if the soundcard is on IRQ 10). > > > > > > does such a change combined with v=3 fix the latencies you are seeing? > > > > With L2, 1:3, max_sectors_kb=256, and the above change, the performance > > is truly amazing. Over 20 million interrupts, on a 600Mhz machine, the > > worst latency I was able to trigger was 46 usecs. There does not seem > > to be any adverse affect on any aspect of the system. > > > > 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.
I have also found that if I stress the VM subsystem severely using sysbench --threads=128 --test=memory, jackd will not start, eventually its watchdog thread will kill it before it opens the audio ports. It seems likely that under pressure the mlockall() would never return. I can add some debugging code to jackd if you need to see which system call is timing out.
Lee
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