Re: [linux-audio-user] xrun madness

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Subject: Re: [linux-audio-user] xrun madness
From: R Parker (rtp405_AT_yahoo.com)
Date: Tue Oct 19 2004 - 09:16:45 EEST


Hi Joel,

I have no solution for you or me. I run raid5 on an
ICP vortex GDT8543RZ. No amount of tuning on this Tyan
Tiger SMP MoBo running 2.4.26-1.ll.rh90.ccrma with a
single AMD Athlon(tm) MP 2600+ will eliminate xruns.

I've tried pci bus latency timings, shutting down
processes, IRQ ordering and every other tuning
experiment ever seen on LAU. It sounds like you are
experiencing more xruns than I am. I have managed to
run a number of sessions without problems during print
but my confidance in this hardware is very low.

I used to run this controler on a Tyan Tiger with dual
PII 450 CPU's and couldn't produce xruns when I tried.
But this was a couple years ago.

When I first began running the controler in this new
MoBo it was an SMP system and I couldn't produce an
xrun if I tried. Unfortunately I ran into a bug with
the raid controler and the 66mhz pci bus that prevents
the system from booting. I never tried forcing 33hmz
on the MoBo but probably should have. I haven't a clue
why the system ran for a month without incident and
then suddenly that bug appears.

I don't know what to make of your experience or mine.
It's been a long time since I've been interested in
thinking about this stuff. It seems like you're doing
a much better job of analyzing hardware performance
than I did.

If nothing else, my experiences lead me to believe
these performance issues are not because of the
capabilities of the scsi system, the hardare raid
controlers or their drivers. Maybe it's a combination
of hardware devices or maybe it's software.

I wasn't going to reply but what the heck. If nothing
else, you know that you're not alone or something. :)

ron

--- Joel White <cv223_AT_comcast.net> wrote:

> Hi, all,
>
> Sorry for the length, here, but I'm out of ideas for
> things to try!
>
> Back in June, I wrote to the list lamenting xruns in
> my system using
> jackd and ardour with a Delta 1010LT and an Adaptec
> 7890 SCSI
> controller. I was trying out early 2.6 kernels, but
> ended up going back
> to a 2.4.23 with low latency patches, but there were
> still xruns with
> the 2.4.23 kernel. I came across info suggesting
> the problem was the
> Adaptec controller:
>
> http://eca.cx/lau/2004/06/0000.html
>
> I ended up adding an IDE drive to use for audio, and
> things seemed to work:
>
> http://eca.cx/lau/2004/06/0026.html
>
> I've continue fussing with the system to try and
> figure out the SCSI
> problem. "Why bother?" you ask? Well, my system is
> still on the SCSI
> Raid0 and occassionally I still get an xrun (last
> night, the
> "occasional" became "in the middle of 3 or 4
> attempts to lay down basic
> tracks with the band" - arrggh!), even when I've
> shut off just about all
> processes. I can really pile up the xruns while
> recording to the IDE
> drive by coping a big file on the SCSI Raid0,
> suggesting again a problem
> with the Adaptec.
>
> I wrote to Justin Gibbs, who worked on the aic7xxx
> driver. He said
> that the contention expressed on the ST Audio
> website (referenced in the
> first message linked above) that the Adaptec keeps
> steady access to the
> PCI bus was "complete hogwash." He mentioned that
> there may be problems
> with the latency timer settings on the devices, so
> I've tried just about
> every possible combination of latency timer settings
> for the AIC7890 and
> the 1010LT, but nothing changes the number of xruns
> when recording to
> the SCSI Raid0 (about 30 in a 1 min recording
> session, 8 channels, -n 2
> -p 256). So that doesn't seem to be it.
>
> Justin expressed doubts about whether the AIC7890
> was the problem, but
> it is clear that the xruns are linked to disk writes
> (I monitored iostat
> while recording, and the xruns occured when the
> disks were written to).
> This seems rather damning, but I've found that I can
> record to the SCSI
> Raid0 with no xruns at all when running Capture
> only, with periods down
> to 128. Iostat shows the same amount of disk
> activity. Interestingly,
> running in Duplex mode on the SCSI Raid0, I cannot
> eliminate xruns even
> with the largest period possible (something like -n
> 2 -p 2048) - I will
> still get occasional xruns.
>
> In an effort to track down the problem, with Lee
> Revell's help (thanks,
> Lee!) I've tried out the recent 2.6.9-rc2-mm4-VP-S7
> kernel to take
> advantage of its kernel latency tracing
> capabilities. Turning on all
> the preempt and latency doo-dads shows that the max
> kernel latency to be
> around 200 - 400 usec when recording to either the
> SCSI Raid0 or IDE
> disks. This kernel latency is far below the 5.8ms
> period time (-p 256
> -r 44100). Unfortunately, I still get xruns when
> recording to either
> disk (about 30 in 30 sec of recording). The xrun
> diagnostics don't
> really tell me much, either. I get a lot of:
>
> Oct 18 22:09:38 darth XRUN: pcmC0D0p
> Oct 18 22:09:38 darth [<e0a316a0>]
> snd_pcm_period_elapsed+0x280/0x3f0
> [snd_pcm]
> Oct 18 22:09:38 darth [<c02e1613>]
> schedule+0x403/0x7d0
> Oct 18 22:09:38 darth [<c0133516>]
> handle_IRQ_event+0x36/0x70
> Oct 18 22:09:38 darth [<c0111608>] mcount+0x14/0x18
> Oct 18 22:09:38 darth [<e0a447f6>]
> snd_ice1712_interrupt+0x1a6/0x230
> [snd_ice171
> 2]
> Oct 18 22:09:38 darth [<c0133516>]
> handle_IRQ_event+0x36/0x70
> Oct 18 22:09:38 darth [<c0133c90>]
> do_hardirq+0x70/0xe0
> Oct 18 22:09:38 darth [<c0133e24>]
> do_irqd+0x124/0x1f0
> Oct 18 22:09:38 darth [<c0132b5b>] kthread+0xbb/0xc0
> Oct 18 22:09:38 darth [<c0133d00>] do_irqd+0x0/0x1f0
> Oct 18 22:09:38 darth [<c0132aa0>] kthread+0x0/0xc0
> Oct 18 22:09:38 darth [<c0102779>]
> kernel_thread_helper+0x5/0xc
> Oct 18 22:09:38 darth XRUN: pcmC0D0p
> Oct 18 22:09:38 darth [<e0a316a0>]
> snd_pcm_period_elapsed+0x280/0x3f0
> [snd_pcm]
> Oct 18 22:09:38 darth [<c02e1613>]
> schedule+0x403/0x7d0
> Oct 18 22:09:38 darth [<c0133516>]
> handle_IRQ_event+0x36/0x70
> Oct 18 22:09:38 darth [<c0111608>] mcount+0x14/0x18
> Oct 18 22:09:38 darth [<e0a447f6>]
> snd_ice1712_interrupt+0x1a6/0x230
> [snd_ice171
> 2]
> Oct 18 22:09:38 darth [<c0133516>]
> handle_IRQ_event+0x36/0x70
> Oct 18 22:09:38 darth [<c0133c90>]
> do_hardirq+0x70/0xe0
> Oct 18 22:09:38 darth [<c0133e24>]
> do_irqd+0x124/0x1f0
> Oct 18 22:09:38 darth [<c0132b5b>] kthread+0xbb/0xc0
> Oct 18 22:09:38 darth [<c0133d00>] do_irqd+0x0/0x1f0
> Oct 18 22:09:38 darth [<c0132aa0>] kthread+0x0/0xc0
> Oct 18 22:09:38 darth [<c0102779>]
> kernel_thread_helper+0x5/0xc
> Oct 18 22:10:10 darth XRUN: pcmC0D0p
> Oct 18 22:10:10 darth [<e0a316a0>]
> snd_pcm_period_elapsed+0x280/0x3f0
> [snd_pcm]
> Oct 18 22:10:10 darth [<c02e1613>]
> schedule+0x403/0x7d0
> Oct 18 22:10:10 darth [<c0133516>]
> handle_IRQ_event+0x36/0x70
> Oct 18 22:10:10 darth [<c0111608>] mcount+0x14/0x18
> Oct 18 22:10:10 darth [<e0a447f6>]
> snd_ice1712_interrupt+0x1a6/0x230
> [snd_ice171
> 2]
> Oct 18 22:10:10 darth [<c0133516>]
> handle_IRQ_event+0x36/0x70
> Oct 18 22:10:10 darth [<c0133c90>]
> do_hardirq+0x70/0xe0
> Oct 18 22:10:10 darth [<c0133e24>]
> do_irqd+0x124/0x1f0
> Oct 18 22:10:10 darth [<c0132b5b>] kthread+0xbb/0xc0
> Oct 18 22:10:10 darth [<c0133d00>] do_irqd+0x0/0x1f0
> Oct 18 22:10:10 darth [<c0132aa0>] kthread+0x0/0xc0
> Oct 18 22:10:10 darth [<c0102779>]
> kernel_thread_helper+0x5/0xc
>
> If anyone can help interpret this, I'm all
> ears/eyes!
>
> Under this kernel, running in Capture mode does not
> generate any xruns,
> but jackd halts ardour after about a minute of
> recording with a
> "subgraph starting at ardour timed out" error.
> Capture mode with the
> 2.4.23 kernel seems to work fine recording to either
> disk.
>
> One more bit of info: Running jackd in verbose mode,
> under 2.4.23 the
> max usec runs around 800-1000 when there are no
> xruns (still well below
> the 5.8ms period). Under 2.4.9, the max usec run
> between 1100-2000 (odd
> that it is higher with the different kernel, but
> still below the 5ms).
> Most xruns are below 1 ms.
>
> Oh, and I _never_ get an xrun during playback, even
> in Duplex mode.
>
> I have a Gentoo system, so after seeing recent
> messages about potential
> issue with Gentoo, I tried booting the Demudi LiveCD
> to test things. I
> didn't get far - with no clients, qjackctl showed
> frequent xruns "just
> idling." I figured I'd stick to debugging the
> Gentoo system, since it
> seemed to be closer to working.
>
=== message truncated ===

                
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