Re: [patch] Real-Time Preemption, -RT-2.6.10-rc2-mm3-V0.7.32-15

[Gene Heskett]

On Friday 10 December 2004 05:53, Ingo Molnar wrote:
>* Ingo Molnar <mingo@xxxxxxx> wrote:
>> this smells too. [...]

Humm, something else does too Ingo.  Amanda failed on this
machine last night, and so did an amcheck just now, returning this:

[amanda@coyote driver]$ amcheck Daily
Amanda Tape Server Host Check
-----------------------------
Holding disk /dumps: 26444 MB disk space available, using 25944 MB
amcheck-server: slot 8: date 20041210 label Dailys-8 (active tape)
amcheck-server: slot 9: date 20041124 label Dailys-9 (exact label
match)
NOTE: skipping tape-writable test
Tape Dailys-9 label ok
Server check took 0.386 seconds

Amanda Backup Client Hosts Check
--------------------------------
WARNING: coyote: selfcheck reply timed out.
Client check: 2 hosts checked in 22.199 seconds, 1 problem found

(brought to you by Amanda 2.4.5b1-20041122)
------------------
This was while running 32-12, which otherwise feels good and gave
me no other indication of a problem.  I've also looked at the log,
but its silent on this subject.  I'll get the latest and try it.

>found two brown-paperbag bugs that caused bad latencies in the -RT
>kernel: when i added PREEMPT_DIRECT (which first showed up in
> -32-10) i also added a missed-reschedule bug to try_to_wake_up()
> and to mutex/semaphore-unlock (__up()). Oops.
>
>i dont think this bug could explain a msec-range latency because the
>syscall return path should catch the missed reschedule and it would
> need continuous syscall execution in the milliseconds range by a
> lowprio task for a latency to be transported to latencytest, but
> certainly the bug doesnt help latencies. The -32-15 kernel can be
> downloaded from the usual place:
>
> http://redhat.com/~mingo/realtime-preempt/
>
>other changes in -32-15: more work on the tracer, cleaner trace
> output and the tracing of syscall entries and returns, with
> arguments and return values displayed as well (i.e. a simple strace
> variant). Here is how a syscall now looks like in
> /proc/latency_trace:
>
> loop-tes-3885  0....  100µs > sys_getppid (002fcffc 00000001
> 0000007b) loop-tes-3885  0....  101µs+: sys_getppid
> (sysenter_past_esp) loop-tes-3885  0d...  103µs < (3868)
>
>'< (return-val)' is the syscall return value, '> sys_name(params)'
> is the syscall itself. (note that the return path is also used by
> interrupts, so it's not purely a syscall-return point) This makes
> it easier to track userspace execution.
>
>	Ingo
>-
>To unsubscribe from this list: send the line "unsubscribe
> linux-kernel" in the body of a message to majordomo@xxxxxxxxxxxxxxx
>More majordomo info at  http://vger.kernel.org/majordomo-info.html
>Please read the FAQ at  http://www.tux.org/lkml/

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
99.30% setiathome rank, not too shabby for a WV hillbilly
Yahoo.com attorneys please note, additions to this message
by Gene Heskett are:
Copyright 2004 by Maurice Eugene Heskett, all rights reserved.

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/