Re: 2.5.64-mm2->4 hangs on contest

[Mike Galbraith]

At 11:05 AM 3/10/2003 +0100, Mike Galbraith wrote:
>At 08:12 PM 3/10/2003 +1100, Con Kolivas wrote:
>>On Mon, 10 Mar 2003 18:05, Mike Galbraith wrote:
>> > At 01:29 PM 3/10/2003 +1100, you wrote:
>> > >Tried running contest on 2.5.64-mm2 and mm4 and had the same thing 
>> happen.
>> > > It will hang reliably during process_load. I tried not running
>> > > process_load but it would still get stuck in one of the other loads
>> > > (either a tar load or list load). I can simply stop contest at that 
>> stage
>> > > but then the machine wont work well hanging at the console after a 
>> minute
>> > > or so. This started at mm2 (doesn't happen with mm1).
>> > >
>> > >Here is the sysrq-p and sysrq-t output during process_load (which hangs
>> > > every time):
>> >
>> > hmm, the below looks interesting to me...
>> >
>> > >ksoftirqd/0   R C129A000     2      1             3       (L-TLB)
>> > >Call Trace:
>> > >  [<c0118f3e>] ksoftirqd+0x5e/0x9c
>> > >  [<c0118ee0>] ksoftirqd+0x0/0x9c
>> > >  [<c0106f1d>] kernel_thread_helper+0x5/0xc
>> >
>> > I see that too with irman.  You could try renicing the shell you start
>> > contest from to >= +12.  With irman, what appears to be cpu starvation
>> > ceases to be a problem at exactly +12.  I also see kapmd constantly 
>> wanting
>> > to run but not being serviced.
>>
>>Contest uses a modified process load from irman so it exhibits similar
>>behaviour. Not sure what +12 actually tells me though :-(
>
>Aha!  No wonder your symptoms look so similar.  +12 is just a magic number 
>that works... found by trusty old trial and error method.  What I wanted 
>to see was if your hang would also go away with the same magic number, or 
>if renicing with any value helped you at all.
>
>>My simplistic understanding is that the pipe task in process_load gets
>>constantly elevated as "interactive" by the new scheduler, and nothing else
>>ever happens.
>
>Appears so.  I can make it "work" by doing a dinky (butt ugly:) tweak in 
>activate_task().

Oh, what the heck.  Even a butt ugly patch that works has informational 
value.  Can you try the attached please?  If it works for you too, maybe 
it'll tell Ingo something.

The numbers irman spits out with this (cough cough) patch are mucho better 
than stock, and better than the ones I get once in a while when it (rare) 
doesn't starve me to death with combo.

         -Mike