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SubjectRe: [patch 0/9] x86_64: reliable TSC-based gettimeofday

* jbohac@suse.cz <jbohac@suse.cz> wrote:

> This implementation allows the current time to be approximated by
> reading the CPU's TSC even on SMP machines with unsynchronised TSCs.
> This allows us to have a very fast gettimeofday() vsyscall on all SMP
> machines supporting the RDTSCP instruction (AMD) or having
> synchronised TSCs (Intel).
>
> Inter-CPU monotonicity can not, however, be guaranteed in a vsyscall,
> so vsyscall is not used by default. Still, the syscall version of
> gettimeofday is a lot faster using the TSC approximation instead of
> other hardware timers.

ok, this looks mostly good to me - but this definitely should be based
/ontop/ of the x86_64 GTOD code. I.e. ontop of these patches in -mm:

generic-vsyscall-gtod-support-for-generic_time.patch
generic-vsyscall-gtod-support-for-generic_time-tidy.patch
time-x86_64-hpet_address-cleanup.patch
revert-x86_64-mm-ignore-long-smi-interrupts-in-clock-calibration.patch
time-x86_64-split-x86_64-kernel-timec-up.patch
time-x86_64-split-x86_64-kernel-timec-up-tidy.patch
time-x86_64-split-x86_64-kernel-timec-up-fix.patch
reapply-x86_64-mm-ignore-long-smi-interrupts-in-clock-calibration.patch
time-x86_64-convert-x86_64-to-use-generic_time.patch
time-x86_64-convert-x86_64-to-use-generic_time-fix.patch
time-x86_64-convert-x86_64-to-use-generic_time-tidy.patch
time-x86_64-hpet-fixup-clocksource-changes.patch
time-x86_64-tsc-fixup-clocksource-changes.patch
time-x86_64-re-enable-vsyscall-support-for-x86_64.patch
time-x86_64-re-enable-vsyscall-support-for-x86_64-tidy.patch

also, note that there is a new TSC synchronization check code in -mm as
well:

x86-rewrite-smp-tsc-sync-code.patch

this should be ontop of that too. (and ontop of the high-res timers
queue)

Ingo
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