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Ingo Molnar wrote: > * Ian Kent <raven@themaw.net> 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 <davidsen@tmr.com> CTO TMR Associates, Inc Doing interesting things with small computers since 1979 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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