On 3 May 2008, Jeff Dike told this:
> On Sat, May 03, 2008 at 12:21:15AM +0100, Nix wrote:
>> With this patch (migrating most of the work into os_nsecs(), with a
>> non-NO_HZ version doing skew computations too, atop your first patch,
>> and making a couple of variables static for good measure), I still had
>> no luck:
>
>>From a quick look, this seems right. And this would be the gold
> standard of preventing UML from seeing time going backwards.
Oh. And it still doesn't work. Damn.
>> So there's basically nothing unusual here. The first gettimeofday() call
>> after the jump, and *whoompf* we're off into the magic land of looping
>> with no extra syscalls to speak of at all.
>
> This was with a solid hang? The thing is still handling page faults
> from something at the end of that trace. I would try again, making
> sure it's a solid hang, and including enough of the trace so that you
> stop seeing page faults:
> waitpid(9963, [{WIFSTOPPED(s) && WSTOPSIG(s) == SIGSEGV}])
> and system calls (WSTOPSIG(s) == 133) and see what's happening at that
> point.
I gave it thirty seconds after the time change. After that
gettimeofday() there is *nothing* (which is unsurprising; the kernel
thread is stuck in a tight loop trying to decrement 2^64 down to 0 by
repeated subtraction... there's not much time for syscalls there.)
> And if you never stop seeing page faults or system calls, then that's
> interesting too.
Howzabout if we never see any after that gettimeofday()? :/
--
`If you are having a "ua luea luea le ua le" kind of day, I can only
assume that you are doing no work due [to] incapacitating nausea caused
by numerous lazy demons.' --- Frossie
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