[PATCH v6] powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE

[Santosh Sivaraj]

* Naveen N. Rao <naveen.n.rao at linux.vnet.ibm.com> wrote (on 2017-10-11 07:04:43 +0000):

> Hi Santosh,
> This seems to have gone from v4 to v6 -- did I miss v5?

Nope, this is indeed v5, a typo :-(
>
> On 2017/10/10 11:10PM, Santosh Sivaraj wrote:
> > 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 times.
> > 
> > (Non-coarse clocks are also included just for completion)
> > 
> > clock-gettime-realtime: syscall: 172 nsec/call
> > clock-gettime-realtime:    libc: 28 nsec/call
> > clock-gettime-realtime:    vdso: 22 nsec/call
> > clock-gettime-monotonic: syscall: 171 nsec/call
> > clock-gettime-monotonic:    libc: 30 nsec/call
> > clock-gettime-monotonic:    vdso: 25 nsec/call
> > clock-gettime-realtime-coarse: syscall: 153 nsec/call
> > clock-gettime-realtime-coarse:    libc: 16 nsec/call
> > clock-gettime-realtime-coarse:    vdso: 10 nsec/call
> > clock-gettime-monotonic-coarse: syscall: 167 nsec/call
> > clock-gettime-monotonic-coarse:    libc: 17 nsec/call
> > clock-gettime-monotonic-coarse:    vdso: 11 nsec/call
> > 
> > CC: Benjamin Herrenschmidt <benh at kernel.crashing.org>
> > Signed-off-by: Santosh Sivaraj <santosh at fossix.org>
> > ---
> >  arch/powerpc/kernel/asm-offsets.c         |  2 +
> >  arch/powerpc/kernel/vdso64/gettimeofday.S | 67 ++++++++++++++++++++++++++-----
> >  2 files changed, 58 insertions(+), 11 deletions(-)
> 
> ... and no changes since the last rev?

There is that one line change of label. But otherwise its the same.
> 
> It is better to post new versions in a separate thread and to include 
> the changelog for easier review.
>

Sure.

Thanks,
Santosh
> 
> - Naveen
> 

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