From fcb41a2030abe0eb716ef0798035ef9562097f42 Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Mon, 22 Apr 2013 09:29:33 +0000 Subject: powerpc: Add VDSO version of time On 04/18/2013 07:38 PM, Anton Blanchard wrote: > Since you are only reading one long you shouldn't need to check the > update count and loop, you will always see a consistent value. The > system call version of time() just does an unprotected load for example. Fixed. > With the above change and with Michael's comments covered (decent > changelog entry and Signed-off-by): > > Acked-by: Anton Blanchard Thanks for the review, below the updated patch: From: Adhemerval Zanella This patch implement the time syscall as vDSO. The performance speedups are: Baseline PPC32: 380 nsec Baseline PPC64: 350 nsec vdso PPC32: 20 nsec vsdo PPC64: 20 nsec Tested on 64 bit build with both 32 bit and 64 bit userland. Acked-by: Anton Blanchard Signed-off-by: Adhemerval Zanella Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/kernel/vdso.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/powerpc/kernel/vdso.c') diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c index 1b2076f049ce..d4f463ac65b1 100644 --- a/arch/powerpc/kernel/vdso.c +++ b/arch/powerpc/kernel/vdso.c @@ -113,6 +113,10 @@ static struct vdso_patch_def vdso_patches[] = { CPU_FTR_USE_TB, 0, "__kernel_get_tbfreq", NULL }, + { + CPU_FTR_USE_TB, 0, + "__kernel_time", NULL + }, }; /* -- cgit