Messages in this thread |  | | Date | Thu, 1 Feb 2007 12:34:40 +0100 | From | Ingo Molnar <> | Subject | Re: [patch 0/9] x86_64: reliable TSC-based gettimeofday |
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* 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)
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