Strange xmms deaths under high disk load

From: Måns Rullgård
Date: Mon Jan 26 2004 - 18:07:08 EST


I have encountered a very strange (to me, at least) error. I can
reliably cause xmms to crash by simply doing some intensive disk IO.
Copying a few hundred megabytes usually does it. After about 20
seconds of heavy disk IO, xmms will die with this message:

** WARNING **: snd_pcm_wait: Input/output error
Xlib: unexpected async reply (sequence 0x2ef5c)!

The hex number varies.

The machine is an Alpha SX164 running Linux 2.6.2-rc2 patched up to
ALSA 1.0.1. The problem has been around for quite a while, probably
also with kernel 2.4.21, though I can't confirm that at the moment.
The sound card is a cmi8738.

If I play music with TCVP instead, it keeps playing, but sound is
choppy at intervals. Below is vmstat output during a copying.

procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
0 0 0 86128 3424 165920 0 0 66 66 24 4 23 23 54 0
0 0 0 86128 3424 165920 0 0 0 0 1131 1352 17 14 69 0
0 0 0 86128 3424 165920 0 0 0 0 1128 1360 13 4 84 0
0 0 0 86128 3424 165920 0 0 0 0 1129 1351 13 4 84 0
0 0 0 86128 3424 165920 0 0 0 153 1142 1361 14 3 83 0
0 0 0 86128 3424 165920 0 0 0 0 1127 1353 14 4 83 0
0 0 0 86128 3424 165920 0 0 0 0 1128 1348 12 3 84 0
0 0 0 86128 3424 165920 0 0 0 0 1130 1344 17 15 69 0
0 0 0 86000 3424 166048 0 0 128 0 1132 1356 13 3 84 0
1 1 0 71648 3472 179992 0 0 7064 81 1255 1540 16 26 44 14
2 0 0 34912 3480 216296 0 0 18081 88 1409 1792 20 61 1 18
1 0 0 2016 3464 248720 0 0 19420 0 1423 1795 20 65 0 15
14 1 0 2400 3392 246544 0 0 11632 24929 1596 1489 16 60 1 23
11 2 0 2400 3392 246368 0 0 768 26112 969 626 25 71 0 3
3 0 0 1952 3392 248552 0 0 10112 6310 1250 1396 29 51 0 20
1 0 0 1568 3376 248760 0 0 18328 4 1409 1794 20 63 0 17
1 0 0 2336 1696 249464 0 0 19576 0 1417 1858 20 68 0 11
7 1 0 2400 1704 248160 0 0 8904 22984 1230 955 16 70 1 13
11 0 0 3040 1704 248160 0 0 0 33704 696 58 10 90 0 0
1 1 0 2016 1704 249840 0 0 13980 88 1345 1710 29 60 0 10
0 1 0 2016 1696 250056 0 0 17920 0 1479 1903 22 65 0 13
1 0 0 2016 1712 250616 0 0 17968 0 1605 2085 27 66 0 7
16 0 0 2016 1736 249352 0 0 3224 53457 1284 379 11 86 0 4
4 0 0 2208 1736 250448 0 0 9736 88 1558 1793 41 45 2 12
1 1 0 2272 1728 250368 0 0 10200 105 1406 1691 46 42 0 12
4 1 0 2272 1728 250544 0 0 11024 0 1362 1790 53 40 0 8
2 0 0 2336 1720 250480 0 0 16760 33 1488 1916 26 62 0 12
19 0 0 2976 1720 248904 0 0 5644 53328 1537 682 12 81 0 6
2 0 0 1760 1744 251080 0 0 12216 73 1365 1700 31 57 0 12
1 0 0 1568 1736 251400 0 0 18520 72 1410 1809 21 66 0 13
0 1 0 1568 1736 251368 0 0 17316 20 1405 1759 20 61 0 19
13 0 0 1888 1736 250632 0 0 5352 32205 1090 625 11 74 0 15
1 1 0 2528 1736 250608 0 0 1756 21332 965 590 35 56 0 8
4 0 0 1760 1696 251352 0 0 20040 0 1428 1825 21 69 0 10
1 1 0 1504 1696 251824 0 0 15164 16 1366 1742 24 65 0 11
6 1 0 2400 1696 249424 0 0 16460 27005 2106 1992 19 68 0 13

Whenever there was a high value for "bo" the sound was really choppy.

I don't mind an occasional glitch in the sound too much, but the fact
that xmms died makes me a little nervous. What's worse, yesterday it
even corrupted the playlist file on disk rather badly.

The filesystems are XFS on device-mapper on raid1 over raid0 on four
disks connected to a hpt374 controller.

Should I just call it an xmms bug, or should I start digging for
hardware problems or kernel bugs?

--
Måns Rullgård
mru@xxxxxx
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