Subject: Re: [linux-audio-dev] kernel preemption patch and 2.4.19
From: Paul Davis (paul_AT_linuxaudiosystems.com)
Date: Wed Jun 02 2004 - 23:41:11 EEST
>What specific benefits have folks seen by turning on the kernel
>preemption patch in a 2.4.19 kernel?
>From the benchmarks that have been done, the preemption patch seems to
have only very small benefits when added to the low latency patch. By
itself, it adds on the order of 80-90% of the low latency patch.
>We found that a nasty system crash was fixed by turning off preemption.
>The crash would happen fairly reliably by switching between virtual
>terminals a number of times. It locked up the system hard. So hard that
>we can't really find the problem in the kernel; we just found a
>work-around basically by trial and error.
[ ... ]
>Also, we are newbies about reporting this kind of crash. Any clues about
>where to report it or ask about it?
compile the kernel with magic-sysrq support. be sure to get back to a
text console before a lock up is expected. when the system locks up,
try using Ctrl-Alt-SysRq-p to find out if the system is stuck in a
loop or something similar. if Ctrl-Alt-SysRq won't work, you have a
completely stuck system and debugging it will be a work of pure
machocism.
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