diff options
| author | Santosh Sivaraj <santosh@fossix.org> | 2017-10-16 11:19:14 +0530 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2017-12-04 15:01:09 +1100 |
| commit | 5c929885f1bb4b77f85b1769c49405a0e0f154a1 (patch) | |
| tree | 25917723f5393257b386deef8f796bb36e71de8d /arch/powerpc/kernel/asm-offsets.c | |
| parent | f0200c02883367f0eb6c9e2f19a8ab6335a52b86 (diff) | |
| download | linux-5c929885f1bb4b77f85b1769c49405a0e0f154a1.tar.gz | |
powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE
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@kernel.crashing.org>
Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Santosh Sivaraj <santosh@fossix.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/kernel/asm-offsets.c')
| -rw-r--r-- | arch/powerpc/kernel/asm-offsets.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index 6b958414b4e036..3f6316bcde4ee9 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -396,6 +396,8 @@ int main(void) /* Other bits used by the vdso */ DEFINE(CLOCK_REALTIME, CLOCK_REALTIME); DEFINE(CLOCK_MONOTONIC, CLOCK_MONOTONIC); + DEFINE(CLOCK_REALTIME_COARSE, CLOCK_REALTIME_COARSE); + DEFINE(CLOCK_MONOTONIC_COARSE, CLOCK_MONOTONIC_COARSE); DEFINE(NSEC_PER_SEC, NSEC_PER_SEC); DEFINE(CLOCK_REALTIME_RES, MONOTONIC_RES_NSEC); |