Re: Realtime Preemption, 2.6.12, Beginners Guide?

[Alistair John Strachan <s0348365@sms.ed.ac.uk>]

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On Friday 08 Jul 2005 12:46, Ingo Molnar wrote:
[snip]
>
> Ok. Could you try to debug this some more? In the -51-17 patch i've
> implemented a new stack-overflow debugging feature: 'stack footprint
> maximum searching'. It is automatically active if you have
> CONFIG_LATENCY_TRACE and CONFIG_DEBUG_STACKOVERFLOW enabled. It will
> track and (if it can be done safely) print out maximum stack usage sites
> immediately. Hopefully this results in better stackdumps. It should
> print similar traces:
>
> ----------------------------->
>
> | new stack-footprint maximum: smartd/1747, 1768 bytes.
>
> ------------|
>  [<c013c1b6>] check_raw_flags+0xb/0x55 (8)
>  [<c013ebeb>] sub_preempt_count+0x1a/0x1c (8)
>  [<c013cb28>] __mcount+0x6a/0x91 (28)
>  [<c013c3ff>] irqs_disabled+0x8/0x19 (16)
>  [<c013c7b5>] ____trace+0x9e/0x208 (4)
>  [<c01142d8>] mcount+0x14/0x18 (24)
>  [<c013c3ff>] irqs_disabled+0x8/0x19 (20)
>  [<c013c7b5>] ____trace+0x9e/0x208 (8)
>  [<c013f145>] trace_stop_sched_switched+0x40/0x17d (8)
>  [...]
>
> i've written a separate, hopefully more robust stack-dumper which is
> used for the above traces. Perhaps in your overflow case it results in
> something usable.

Unfortunately I see nothing like this when the machine crashes. Find attached 
my config, which has CONFIG_4KSTACKS and the options you specified. Are you 
sure this is sufficient to enable it?

Here is an extremely bad digital camera pic from the crash. My debugging 
prowess has evolved to the stage where by I'm using a maximum res vesafb 
console.

However, I'm not at work so it's my own digital camera that I'm using rather 
than work's, and it seems to react badly to the LCD. I hope you can read the 
numbers, if not I'll try to transliterate them for you.

http://devzero.co.uk/~alistair/oops5.jpeg

-- 
Cheers,
Alistair.

personal:   alistair()devzero!co!uk
university: s0348365()sms!ed!ac!uk
student:    CS/CSim Undergraduate
contact:    1F2 55 South Clerk Street,
            Edinburgh. EH8 9PP.

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