Re: [PATCH v8 8/8] powerpc/vdso: Provide __kernel_clock_gettime64() on vdso32

[Christophe Leroy]

Le 09/05/2020 Ã 17:54, Christophe Leroy a ÃcritÂ:
> Le 28/04/2020 Ã 18:05, Arnd Bergmann a ÃcritÂ:
> > On Tue, Apr 28, 2020 at 3:16 PM Christophe Leroy
> > <christophe.leroy@xxxxxx> wrote:
> > > Provides __kernel_clock_gettime64() on vdso32. This is the
> > > 64 bits version of __kernel_clock_gettime() which is
> > > y2038 compliant.
> > >
> > > Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
> >
> > Looks good to me
> >
> > Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx>
> >
> > There was a bug on ARM for the corresponding function, so far it is 
> > unclear
> > if this was a problem related to particular hardware, the 32-bit 
> > kernel code,
> > or the common implementation of clock_gettime64 in the vdso library,
> > see https://github.com/richfelker/musl-cross-make/issues/96
> >
> > Just to be sure that powerpc is not affected by the same issue, can you
> > confirm that repeatedly calling clock_gettime64 on powerpc32, alternating
> > between vdso and syscall, results in monotically increasing times?
>
> I think that's one of the things vdsotest checks, so yes that's ok I think.

Here is the full result with vdsotest:

gettimeofday: syscall: 3715 nsec/call
gettimeofday:    libc: 794 nsec/call
gettimeofday:    vdso: 947 nsec/call
getcpu: syscall: 1614 nsec/call
getcpu:    libc: 484 nsec/call
getcpu:    vdso: 184 nsec/call
clock-gettime64-realtime-coarse: syscall: 3152 nsec/call
clock-gettime64-realtime-coarse:    libc: not tested
clock-gettime64-realtime-coarse:    vdso: 653 nsec/call
clock-getres-realtime-coarse: syscall: 2963 nsec/call
clock-getres-realtime-coarse:    libc: 745 nsec/call
clock-getres-realtime-coarse:    vdso: 553 nsec/call
clock-gettime-realtime-coarse: syscall: 5120 nsec/call
clock-gettime-realtime-coarse:    libc: 731 nsec/call
clock-gettime-realtime-coarse:    vdso: 577 nsec/call
clock-gettime64-realtime: syscall: 3719 nsec/call
clock-gettime64-realtime:    libc: not tested
clock-gettime64-realtime:    vdso: 976 nsec/call
clock-getres-realtime: syscall: 2496 nsec/call
clock-getres-realtime:    libc: 745 nsec/call
clock-getres-realtime:    vdso: 546 nsec/call
clock-gettime-realtime: syscall: 4800 nsec/call
clock-gettime-realtime:    libc: 1080 nsec/call
clock-gettime-realtime:    vdso: 1798 nsec/call
clock-gettime64-boottime: syscall: 4132 nsec/call
clock-gettime64-boottime:    libc: not tested
clock-gettime64-boottime:    vdso: 975 nsec/call
clock-getres-boottime: syscall: 2497 nsec/call
clock-getres-boottime:    libc: 730 nsec/call
clock-getres-boottime:    vdso: 546 nsec/call
clock-gettime-boottime: syscall: 3728 nsec/call
clock-gettime-boottime:    libc: 1079 nsec/call
clock-gettime-boottime:    vdso: 941 nsec/call
clock-gettime64-tai: syscall: 4148 nsec/call
clock-gettime64-tai:    libc: not tested
clock-gettime64-tai:    vdso: 955 nsec/call
clock-getres-tai: syscall: 2494 nsec/call
clock-getres-tai:    libc: 730 nsec/call
clock-getres-tai:    vdso: 545 nsec/call
clock-gettime-tai: syscall: 3729 nsec/call
clock-gettime-tai:    libc: 1079 nsec/call
clock-gettime-tai:    vdso: 927 nsec/call
clock-gettime64-monotonic-raw: syscall: 3677 nsec/call
clock-gettime64-monotonic-raw:    libc: not tested
clock-gettime64-monotonic-raw:    vdso: 1032 nsec/call
clock-getres-monotonic-raw: syscall: 2494 nsec/call
clock-getres-monotonic-raw:    libc: 745 nsec/call
clock-getres-monotonic-raw:    vdso: 545 nsec/call
clock-gettime-monotonic-raw: syscall: 3276 nsec/call
clock-gettime-monotonic-raw:    libc: 1140 nsec/call
clock-gettime-monotonic-raw:    vdso: 1002 nsec/call
clock-gettime64-monotonic-coarse: syscall: 4099 nsec/call
clock-gettime64-monotonic-coarse:    libc: not tested
clock-gettime64-monotonic-coarse:    vdso: 653 nsec/call
clock-getres-monotonic-coarse: syscall: 2962 nsec/call
clock-getres-monotonic-coarse:    libc: 745 nsec/call
clock-getres-monotonic-coarse:    vdso: 545 nsec/call
clock-gettime-monotonic-coarse: syscall: 4297 nsec/call
clock-gettime-monotonic-coarse:    libc: 730 nsec/call
clock-gettime-monotonic-coarse:    vdso: 592 nsec/call
clock-gettime64-monotonic: syscall: 3863 nsec/call
clock-gettime64-monotonic:    libc: not tested
clock-gettime64-monotonic:    vdso: 975 nsec/call
clock-getres-monotonic: syscall: 2494 nsec/call
clock-getres-monotonic:    libc: 745 nsec/call
clock-getres-monotonic:    vdso: 545 nsec/call
clock-gettime-monotonic: syscall: 3465 nsec/call
clock-gettime-monotonic:    libc: 1079 nsec/call
clock-gettime-monotonic:    vdso: 927 nsec/call

Christophe