Re: [patch] voluntary-preempt-2.6.8-rc2-M5

Lee Revell
2004-07-30T22:54:21Z

On Fri, 2004-07-30 at 02:44, Ingo Molnar wrote:
> * Lee Revell <rlrevell@joe-job.com> wrote:
>
> > After running jackd with L2 all night, the only repeated XRUN was this
> > one:
> >
> > ALSA /home/rlrevell/cvs/alsa/alsa-driver/alsa-kernel/core/pcm_lib.c:139: XRUN: pcmC0D2c
> > [<c01066a7>] dump_stack+0x17/0x20
> > [<de93d54b>] snd_pcm_period_elapsed+0x27b/0x3e0 [snd_pcm]
> > [<de979211>] snd_emu10k1_interrupt+0xd1/0x3c0 [snd_emu10k1]
> > [<c01078d7>] handle_IRQ_event+0x47/0x90
> > [<c0107e93>] do_IRQ+0xe3/0x1b0
> > [<c0106268>] common_interrupt+0x18/0x20
> > [<c0146771>] add_to_swap+0x21/0xc0
> > [<c0139446>] shrink_list+0x156/0x4b0
> > [<c01398ed>] shrink_cache+0x14d/0x370
> > [<c013a118>] shrink_zone+0xa8/0xf0
> > [<c013a4ee>] balance_pgdat+0x1be/0x220
> > [<c013a5f9>] kswapd+0xa9/0xb0
> > [<c0104395>] kernel_thread_helper+0x5/0x10
> >
> > This produced a few ~2ms XRUNs. The shrink_zone -> shrink_cache ->
> > shrink_list is a recurring motif.
> >
> > Is this addressed in M2?
>
> not yet. I havent seen this latency yet, nor are there any immediately
> clear clues in the xrun logs you sent. (it would still be nice to check
> out -M2, to see whether with all those configurability changes it
> matches the latencies of L2+your-irq.c-hack.)

I discovered that a few of the XRUN traces were spurious - jackd
apparently does something while stopping and starting that produces an
XRUN trace but that jackd does not consider an error. I will fix this
in jackd. The msync() related XRUN triggered by apt-get is definitely
real.

Here are my results with 2.6.8-rc2-mm1-M5.

max usecs
All IRQs threaded 349
Soundcard IRQ not threaded 227
Soundcard IRQ not threaded + max_sectors_kb -> 64 119

I will test next with 2.6.8-rc2-M5.

Lee