Date: Thu, 1 Jul 1999 23:34:29 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: current@FreeBSD.ORG Subject: Something weird happening w/ SMP -current Message-ID: <199907020634.XAA52990@apollo.backplane.com>
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I'm getting some really odd stuff with recent -current's configured
for SMP. Processes are getting stuck in getblk() and other I/O waits.
It does not appear to occur with UP configuration, only SMP.
I seem to be able to repeat the problem by dd'ing a raw partition from
a SCSI{ disk to /dev/null:
dd if=/dev/rda1d bs=32k of=/dev/null
If I run a 'systat -vm 1' in another window what I see are a bunch of ahc2
interrupts, around 500-1000 per second, and then it just stops. Then a
few seconds later it starts up again. Then it just stops. Then a few
seconds later it starts up again. It is as thought interrupts are being
disabled for long periods of time but the weird thing is that other
interrupts such as clk and rtc continue to work just fine.
When the interrupts stop, dd is stuck in a disk-wait state. I'm sure it
isn't the SCSI bus: I've got three SCSI busses and it occurs on all three.
Plus it does not occur on a UP kernel, only an SMP kernel.
If I run an endless loop in another window (e.g. systat shows 50% idle
on the 2x SMP box), the interrupts appear to work for longer periods of
time before crapping out.
It is very weird. I have no idea what is going on.
-Matt
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