Re: a joint letter on low latency and Linux

David Woodhouse (dwmw2@infradead.org)
Fri, 30 Jun 2000 09:45:33 +0100

lm@bitmover.com said:
> I'm 100% in agreement with the idea that all code paths through the
> kernel should be short and sweet, but that isn't always the case. All
> it takes is one misbehaving driver that hangs onto the CPU too long
> and you missed your deadline.

Don't Do That Then. The driver is broken, not the model. Fix it.

It ought to be possible to devise a test for debugging drivers, similar in
concept to the slab poisoning, which will BUG() if a process has blocked for
too long. Could the NMI watchdog or something similar be extended to do
this? Would we get a useful backtrace?

This can automatically find many of the instances of badly-behaved code
which causes high latency, but can also be turned off in production kernels.

--
dwmw2






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