2017-01-13 13:34-0200, Marcelo Tosatti: > On Fri, Jan 13, 2017 at 04:18:04PM +0100, Radim Krcmar wrote: >> 2017-01-13 10:01-0200, Marcelo Tosatti: >> > Expose the realtime host clock and save the TSC value >> > used for the clock calculation. >> > >> > Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx> >> > >> > --- >> > arch/x86/kvm/x86.c | 38 ++++++++++++++++++++++++++++++++++++++ >> > 1 file changed, 38 insertions(+) >> > >> > Index: kvm-ptpdriver/arch/x86/kvm/x86.c >> > =================================================================== >> > --- kvm-ptpdriver.orig/arch/x86/kvm/x86.c 2017-01-13 08:59:03.015895353 -0200 >> > +++ kvm-ptpdriver/arch/x86/kvm/x86.c 2017-01-13 09:04:46.581415259 -0200 >> > @@ -1139,6 +1139,8 @@ >> > >> > u64 boot_ns; >> > u64 nsec_base; >> > + u64 wall_time_sec; >> > + u64 wall_time_snsec; >> >> The leading "s" in "snsec" looks like a copy-paste residue. > > Just copying the userspace vsyscall interface. Oh, so the "s" means "sub-" for sub-nanosecond precision. >> > }; >> > >> > static struct pvclock_gtod_data pvclock_gtod_data; >> > @@ -1162,6 +1164,9 @@ >> > vdata->boot_ns = boot_ns; >> > vdata->nsec_base = tk->tkr_mono.xtime_nsec; >> > >> > + vdata->wall_time_sec = tk->xtime_sec; >> > + vdata->wall_time_snsec = tk->tkr_mono.xtime_nsec; >> >> Using tk->tkr_mono offsets for real time seems wrong -- what happens if >> the real time is half a second shifted from monotonic time? > > Both the userspace vsyscall interface and getnstimeofday > use it for realtime clock. > > Monotonic clock adds the offset: > > vdata->monotonic_time_snsec = tk->tkr_mono.xtime_nsec > + > ((u64)tk->wall_to_monotonic.tv_nsec > << tk->tkr_mono.shift); I see, thanks. Makes me wonder why our monotonic time is correct then, but that is problably thanks to boot_ns. >> If it's ok, then vdata->nsec_base == vdata->wall_time_snsec, so we don't >> need it. > > Just copying the userspace vsyscall interface. > > Do you actually want to change the "s" and unify wall_time_snsec with > nsec_base? The "s" isn't important, even though I don't think we do anything that would justify it, but make use just 8 bytes for both. Renaming nsec_base is ok, but I'm not sure what tk->tkr_mono.xtime_nsec is anymore. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
