Messages in this thread | | | Subject | Re: [patch] voluntary-preempt-2.6.8-rc3-O5 | From | Lee Revell <> | Date | Thu, 12 Aug 2004 18:16:50 -0400 |
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On Wed, 2004-08-11 at 03:31, Ingo Molnar wrote: > * Lee Revell <rlrevell@joe-job.com> wrote: > > > (jackd/12427): 10882us non-preemptible critical section violated 400 > > us preempt threshold starting at kernel_fpu_begin+0x10/0x60 and ending > > at fast_clear_page+0x75/0xa0 > > to make sure this is a real latency and not some rdtsc weirdness, could > you try the latest version of preempt-timing: > > http://redhat.com/~mingo/voluntary-preempt/preempt-timing-on-2.6.8-rc3-O5-A2 > > this adds jiffies-based latency values to the printout, e.g.: > > (ksoftirqd/0/2): 3860us [3 jiffy] non-preemptible critical section > violated 100 us preempt threshold starting at ___do_softirq+0x1b/0x90 > and ending at cond_resched_softirq+0x57/0x70 > > shows that a 10 jiffy (10 msec) latency happened - which matches the > rdtsc-based 3860 usecs value. >
Here is the preempt-timing violation and accompanying xrun I got when starting jackd. It looks like the jiffies value matches the rdtsc:
ALSA /home/rlrevell/cvs/alsa/alsa-driver/alsa-kernel/core/pcm_lib.c:139: XRUN: pcmC0D2c [<c0106497>] dump_stack+0x17/0x20 [<de92714b>] snd_pcm_period_elapsed+0x27b/0x3e0 [snd_pcm] [<de963171>] snd_emu10k1_interrupt+0xd1/0x380 [snd_emu10k1] [<c011a693>] generic_handle_IRQ_event+0x33/0x60 [<c010765e>] do_IRQ+0xbe/0x180 [<c0106078>] common_interrupt+0x18/0x20 [<c013d28e>] do_no_page+0x4e/0x300 [<c013d6e1>] handle_mm_fault+0xb1/0x150 [<c013c118>] get_user_pages+0x138/0x3e0 [<c013d828>] make_pages_present+0x68/0x90 [<c013ef5f>] do_mmap_pgoff+0x40f/0x670 [<c010b245>] sys_mmap2+0x75/0xb0 [<c0105e57>] syscall_call+0x7/0xb (jackd/1359): 9174us [10 jiffy] non-preemptible critical section violated 400 us preempt threshold starting at do_IRQ+0x19/0x180 and ending at do_IRQ+0x121/0x180 [<c0106497>] dump_stack+0x17/0x20 [<c0113e5b>] sub_preempt_count+0x4b/0x60 [<c01076c1>] do_IRQ+0x121/0x180 [<c0106078>] common_interrupt+0x18/0x20 [<c013d28e>] do_no_page+0x4e/0x300 [<c013d6e1>] handle_mm_fault+0xb1/0x150 [<c013c118>] get_user_pages+0x138/0x3e0 [<c013d828>] make_pages_present+0x68/0x90 [<c013ef5f>] do_mmap_pgoff+0x40f/0x670 [<c010b245>] sys_mmap2+0x75/0xb0 [<c0105e57>] syscall_call+0x7/0xb
Lee
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