Hi,
I think I may have found the cause of the pst timeout panics. I'm using
the Promise SX6000 RAID on -CURRENT, using the pst driver. Unfortunately,
under sufficiently high I/O load, the box starts printing:
"pst: timeout mfa=0x00327b90 cmd=0x01"
The 'mfa' address varies. It starts printing more and more rapidly, and
then eventually the machine wedges solid. Sometimes it makes it to:
"panic: timeout table full"
Here's what I think is happening. Two timeouts are being scheduled every
time a timeout triggers, because pst_timeout schedules a timeout before
calling pst_rw to retry the operation. Then pst_rw schedules ANOTHER
timeout. Both of these timeouts call pst_timeout, so they double every 10
seconds until there are a large enough number of timeouts firing, retrying
the same I/O operation, that the table fills and the machine panics.
Check out the following diff
http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/dev/pst/pst-raid.c.diff?r1=1.8&r2=1.9&f=h
This is where pst_rw was changed to schedule its own timeouts, but the
timeout function didn't have its removed.
Do you think this could be the correct explanation? It seems like once
pst_timeout is called, the machine is doomed... I'm recompiling my kernel
now to test the fix under load.
--Aaron
Index: /sys/dev/pst/pst-raid.c
===================================================================
RCS file: /usr/cvs/src/sys/dev/pst/pst-raid.c,v
retrieving revision 1.11
diff -u -r1.11 pst-raid.c
--- /sys/dev/pst/pst-raid.c 24 Aug 2003 17:54:17 -0000 1.11
+++ /sys/dev/pst/pst-raid.c 8 Sep 2003 02:32:58 -0000
@@ -316,11 +316,6 @@
mtx_unlock(&request->psc->iop->mtx);
return;
}
- if (dumping)
- request->timeout_handle.callout = NULL;
- else
- request->timeout_handle =
- timeout((timeout_t*)pst_timeout, request, 10 * hz);
if (pst_rw(request)) {
iop_free_mfa(request->psc->iop, request->mfa);
biofinish(request->bp, NULL, EIO);
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