Date: Thu, 1 Jul 1999 23:54:28 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: current@FreeBSD.ORG Subject: Re: Something weird happening w/ SMP -current Message-ID: <199907020654.XAA53043@apollo.backplane.com> References: <199907020634.XAA52990@apollo.backplane.com>
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: 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
:
Here's some more info. If the dd is stuck and systat -vm 1 is showing
no interrupts occuring on, for example, ahc2 (irq17), and I then do
something that causes an interrupt to occur on mux (irq19), which I
guess is ahc1, ahc2 then starts working... until it gets stuck again,
that is. I can also get ahc2 going again by issuing another dd on ahc2.
For example:
dd if=/dev/rda1d bs=32k of=/dev/null
... let this one run ...
... it gets stuck ...
dd if=/dev/rda1d bs=32k of=/dev/null count=1
... this unsticks the first dd ...
... the first dd runs again ...
... the first dd gets stuck again ...
repeat...
All I can think of is that something is causing the system to lose an
occassional interrupt. There's a race condition somewhere.
-Matt
Matthew Dillon
<dillon@backplane.com>
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