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On Fri, 10 Nov 2006 09:10:06 +0100 Thomas Gleixner <tglx@linutronix.de> wrote: > On Fri, 2006-11-10 at 06:10 +0100, Andi Kleen wrote: > > > > verify_tsc_freq_timer.function = verify_tsc_freq; > > > > verify_tsc_freq_timer.expires = > > > > > > > > > Hmmm. I wish this patch was unnecessary, but I don't see an easy > > > solution. > > > > Very sad. This will make a lot of people unhappy, even to the point > > where they might prefer disabling noidlehz over super slow gettimeofday. > > I assume you at least have a suitable command line option for that, right? > > Yes it is sad. And the sadest part is that AMD and Intel have been asked > to fix that more than 5 years ago. They did not get their brain straight > and now we are the dimwits. > > > Can we get a summary on which systems the TSC is considered unstable? > > Normally we assume if it's stable enough for gettimeofday it should > > be stable enough for longer delays too. > > TSC is simply a nightmare: > > - Frequency changes with CPU clock > - Unsynced across CPUs > - Stops in C3, which makes it completely unusable > > Once you take away periodic interrupts it is simply broken. AMD and > Intel can run in circels, it does not get better. > What is the actual problem? verify_tsc_freq()? If so, could that function use the PIT/pmtimer/etc for working out if the TSC is bust, rather than directly using jiffies? - 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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