Messages in this thread | | | Date | Thu, 9 Oct 2008 13:45:52 -0700 | From | "Alok kataria" <> | Subject | Re: [PATCH] Re: x86_32 tsc/pit and hrtimers |
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On Thu, Oct 9, 2008 at 12:53 PM, Thomas Gleixner <tglx@linutronix.de> wrote: > On Thu, 9 Oct 2008, Jeff Hansen wrote: > >> OK, so are we all agreed that something like clocksource_trust=tsc would be >> the best? > > No, it's per affected device: tsc=trust or tsc=stable or whatever > unintuitive name we want to come up. And it is a modification to TSC > not to the clocksource layer.
Yep, this is cool. I too have a patch in my local tree which does a similar thing i have a tsc_reliable flag which is set right now only when we are running under a VMware hypervisor. Along with marking the no_verify flag for TSC, this patch of mine also skips the TSC synchornization checks.
The TSC synchronization loop which is run whenever a new cpu is brought up is not actually needed on systems which are known to have a reliable TSC. TSC between 2 cpus can be off by a marginal value on such systems and thats okay for timekeeping, since we do check for tsc going back in read_tsc.
Can this reasoning be included and synchronization skipped for all these systems with reliable aka trustworthy TSC's ?
Thanks, Alok > > Thanks, > > tglx > -- > 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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