From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751844AbaBBPny (ORCPT ); Sun, 2 Feb 2014 10:43:54 -0500 Received: from terminus.zytor.com ([198.137.202.10]:45022 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751483AbaBBPnx (ORCPT ); Sun, 2 Feb 2014 10:43:53 -0500 User-Agent: K-9 Mail for Android In-Reply-To: <1391340435-5130-7-git-send-email-stefani@seibold.net> References: <1391340435-5130-1-git-send-email-stefani@seibold.net> <1391340435-5130-7-git-send-email-stefani@seibold.net> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Subject: Re: [PATCH 6/8] cleanup __vdso_gettimeofday From: "H. Peter Anvin" Date: Sun, 02 Feb 2014 07:43:05 -0800 To: stefani@seibold.net, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, x86@kernel.org, tglx@linutronix.de, mingo@redhat.com, ak@linux.intel.com, aarcange@redhat.com, john.stultz@linaro.org, luto@amacapital.net, xemul@parallels.com, gorcunov@openvz.org, andriy.shevchenko@linux.intel.com CC: Martin.Runge@rohde-schwarz.com, Andreas.Brief@rohde-schwarz.com Message-ID: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > >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 >--- > 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.