Current vDSO64 implementation does not have support for coarse clocks
(CLOCK_MONOTONIC_COARSE, CLOCK_REALTIME_COARSE), for which it falls back
to system call, increasing the response time, vDSO implementation reduces
the cycle time. Below is a benchmark of the difference in execution time
with and
Hi Santosh,
[auto build test ERROR on powerpc/next]
[also build test ERROR on v4.13-rc1 next-20170721]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system]
url:
Hi Santosh,
[auto build test ERROR on powerpc/next]
[also build test ERROR on v4.13-rc1 next-20170721]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system]
url:
On Fri, 2017-07-21 at 10:10 +0530, Santosh Sivaraj wrote:
> In case of a bogus clock id, the default case sets 'ret' to -1, which forces
> it
> to fallback to the syscall.
> > I think the solution is probably to do the syscall fallback in asm, and
> > everything else in C.
>
> Ok. That's what
* Michael Ellerman wrote (on 2017-07-20 23:18:26 +1000):
> Santosh Sivaraj writes:
>
> > Current vDSO64 implementation does not have support for coarse
> > clocks (CLOCK_MONOTONIC_COARSE, CLOCK_REALTIME_COARSE), for which it falls
> > back to system
Hi,
> > +static notrace int gettime_syscall_fallback(clockid_t clk_id,
> > +struct timespec *tp)
> > +{
> > + register clockid_t id asm("r3") = clk_id;
> > + register struct timespec *t asm("r4") = tp;
> > + register int nr asm("r0") =
On Fri, Jul 21, 2017 at 07:17:39AM +1000, Benjamin Herrenschmidt wrote:
> > Great patch! Always good to see asm replaced with C.
>
> Yeah ewll ... when C becomes some kind of weird glorifed asm like
> below, I don't see much of a point ;-)
Yeah.
> > > diff --git
On Thu, 2017-07-20 at 23:18 +1000, Michael Ellerman wrote:
> Santosh Sivaraj writes:
>
> > Current vDSO64 implementation does not have support for coarse
> > clocks (CLOCK_MONOTONIC_COARSE, CLOCK_REALTIME_COARSE), for which it falls
> > back to system call. Below is a
Santosh Sivaraj writes:
> Current vDSO64 implementation does not have support for coarse
> clocks (CLOCK_MONOTONIC_COARSE, CLOCK_REALTIME_COARSE), for which it falls
> back to system call. Below is a benchmark of the difference in execution
> time with and without vDSO
Current vDSO64 implementation does not have support for coarse
clocks (CLOCK_MONOTONIC_COARSE, CLOCK_REALTIME_COARSE), for which it falls
back to system call. Below is a benchmark of the difference in execution
time with and without vDSO support.
(Non-coarse clocks are also included just for
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