linux_dsm_epyc7002/arch/powerpc/kernel/vdso64
Santosh Sivaraj 5c929885f1 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>
2017-12-04 15:01:09 +11:00
..
.gitignore [POWERPC] Update .gitignore for new vdso generated files 2007-10-08 08:38:12 -05:00
cacheflush.S [POWERPC] vdso: Fixes for cache block sizes 2007-11-20 13:56:31 +11:00
datapage.S powerpc/vdso64: Use double word compare on pointers 2016-09-29 15:17:57 +10:00
getcpu.S powerpc/booke64: Use SPRG7 for VDSO 2014-03-19 19:57:14 -05:00
gettimeofday.S powerpc/vdso64: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE 2017-12-04 15:01:09 +11:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
note.S [PATCH] powerpc: Merge vdso's and add vdso support to 32 bits kernel 2005-11-11 22:25:39 +11:00
sigtramp.S powerpc: Wrong DWARF CFI in the kernel vdso for little-endian / ELFv2 2013-11-21 09:19:23 +11:00
vdso64_wrapper.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
vdso64.lds.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00