Re: [v6] powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE
From: Michael Ellerman <hidden>
Date: 2017-12-12 11:39:23
On Mon, 2017-10-16 at 05:49:14 UTC, 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@kernel.crashing.org> Reviewed-by: Naveen N. Rao <redacted> Signed-off-by: Santosh Sivaraj <redacted>
Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/5c929885f1bb4b77f85b1769c49405 cheers