Ingo Molnar wrote:
* Ian Kent <[email protected]> wrote:
ah! It passes in a low-res time source into a high-res time
interface (pthread_cond_timedwait()). Could you change the
time(NULL) + 1 to time(NULL) + 2, or change it to:
gettimeofday(&wait, NULL);
wait.tv_sec++;
does this solve the spinning?
Yes, adding in the offset within the current second appears to resolve
the issue. Thanks Ingo.
i'm wondering how widespread this is. If automount is the only app
doing this then _maybe_ we could get away with it by changing
automount?
I don't think the change is unreasonable since I wasn't using an
accurate time in the condition wait, so that's a coding mistake on my
part which I will fix.
thanks Ian for taking care of this and for fixing it!
Linus, Thomas, what do you think, should we keep the time.c change?
Automount is one app affected so far, and it's a borderline case: the
increased (30%) CPU usage is annoying, but it does not prevent the
system from working per se, and an upgrade to a fixed/enhanced automount
version resolves it.
The temptation of using a really (and trivially) scalable low-resolution
time-source (which is _easily_ vsyscall-able, on any platform) for DBMS
use is really large, to me at least. Should i perhaps add a boot/config
option that enables/disables this optimization, to allow distros finer
grained control about this? And we've also got to wait whether there's
any other app affected.
Allow it to be selected by the "features" so that admins can evaluate
the implications without a reboot? That would be a convenient interface
if you could provide it.
--
bill davidsen <[email protected]>
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979
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