Re: [PATCH 6/8] cleanup __vdso_gettimeofday

["H. Peter Anvin" <hpa@zytor.com>]

Even reading the timezone via gettimeofday is the uncommon case... never mind only the timezome.  Whatever you do please don't slow down the common case.

On February 2, 2014 3:27:13 AM PST, stefani@seibold.net wrote:
>From: Stefani Seibold <stefani@seibold.net>
>
>This patch do a little cleanup for the __vdso_gettimeofday() function.
>
>It kick out an unneeded ret local variable and makes the code faster if
>only the timezone is needed.
>
>Signed-off-by: Stefani Seibold <stefani@seibold.net>
>---
> arch/x86/vdso/vclock_gettime.c | 7 ++-----
> 1 file changed, 2 insertions(+), 5 deletions(-)
>
>diff --git a/arch/x86/vdso/vclock_gettime.c
>b/arch/x86/vdso/vclock_gettime.c
>index 743f277..bf969a0 100644
>--- a/arch/x86/vdso/vclock_gettime.c
>+++ b/arch/x86/vdso/vclock_gettime.c
>@@ -259,13 +259,12 @@ int clock_gettime(clockid_t, struct timespec *)
> 
>notrace int __vdso_gettimeofday(struct timeval *tv, struct timezone
>*tz)
> {
>-	long ret = VCLOCK_NONE;
>-
> 	if (likely(tv != NULL)) {
> 		BUILD_BUG_ON(offsetof(struct timeval, tv_usec) !=
> 			     offsetof(struct timespec, tv_nsec) ||
> 			     sizeof(*tv) != sizeof(struct timespec));
>-		ret = do_realtime((struct timespec *)tv);
>+		if (do_realtime((struct timespec *)tv) == VCLOCK_NONE)
>+			return vdso_fallback_gtod(tv, tz);
> 		tv->tv_usec /= 1000;
> 	}
> 	if (unlikely(tz != NULL)) {
>@@ -274,8 +273,6 @@ notrace int __vdso_gettimeofday(struct timeval *tv,
>struct timezone *tz)
> 		tz->tz_dsttime = gtod->sys_tz.tz_dsttime;
> 	}
> 
>-	if (ret == VCLOCK_NONE)
>-		return vdso_fallback_gtod(tv, tz);
> 	return 0;
> }
> int gettimeofday(struct timeval *, struct timezone *)

-- 
Sent from my mobile phone.  Please pardon brevity and lack of formatting.