Re: [RT] fix delay in do_vgettimeofday() inarch/x86_64/kernel/vsyscall.c

From: Fernando Lopez-Lezcano
Date: Sat Dec 10 2005 - 16:24:35 EST


On Fri, 2005-12-09 at 18:33 -0800, john stultz wrote:
> On Fri, 2005-12-09 at 22:38 +0300, Serge Belyshev wrote:
> >
> > There are occasional very very long (30..60 sec) delays happening when calling
> > gettimeofday() vsyscall on x86_64 with 2.6.14-rt22 kernel.
> >
> > These delays come from while() looping over invalid data that are
> > going to be discarded by seqlock.
>
> Ah, good catch! I just included a similar change (moved all the math
> outside the lock) in my own tree.

Is there something equivalent on i386 or this is just an x86_64 thing?
Over the past few days I have seen temporary "lockups" of my machine
(athlon X2 running -2.6.14-rt22, PREEMPT_RT, no hi res timers) lasting
for, say between 10 and 30 seconds. This happens maybe one to three
times in a day (that I noticed). The symptom is that the mouse moves but
everything else is just not doing anything. I don't see anything in the
logs or dmesg after the freeze, or on the servers that machine depends
on (through nfs). During one of those lockups a system load monitor in
the gnome panel was visible and it looked like there was a 100% system
load (or close) in one of the cpus.

-- Fernando


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