Re: [uml-devel] actually useful backtrace from a CPU-chewing hang

[Jeff Dike <jdike@addtoit.com>]

On Fri, May 02, 2008 at 07:55:11PM +0100, Nix wrote:
> No behavioural change :(

Oh well.

> I'm trying something else now, arranging for os_nsecs() itself to do the
> never-backwards stuff on the assumption that something depends on
> monotonic timers not skipping backwards which presently they might
> (there are callers of os_nsecs() outside of os-Linux/time.c, notably in
> kernel/time.c, and currently they see an unadjusted time, jumping
> backwards and forwards and whatever).

This sounds like a reasonable idea.

Another thing you might try is the following:
	get two extra windows
	in one, get a "strace -p uml-pid -o strace.out -tt" ready
	in two, get a "date ; sudo date -s "now-5 sec" ; date" ready
	hit return in one, then in two, then in your UML window
	when the UML gives you another prompt (or you've decided it's
hung), ^C the strace

Look at the times reported by the dates, find the time change in the
strace log, and send the section following that (and a bit before) to
me.

			Jeff

-- 
Work email - jdike at linux dot intel dot com

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