Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752797AbbDEHct (ORCPT ); Sun, 5 Apr 2015 03:32:49 -0400 Received: from www.osadl.org ([62.245.132.105]:40956 "EHLO www.osadl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751104AbbDEHce (ORCPT ); Sun, 5 Apr 2015 03:32:34 -0400 From: Nicholas Mc Guire To: Michal Marek Cc: Masahiro Yamada , Sam Ravnborg , Thomas Gleixner , "H. Peter Alvin" , Joe Perches , John Stultz , Andrew Hunter , Paul Turner , linux-kernel@vger.kernel.org, Nicholas Mc Guire Subject: [PATCH 2/3] time: allow gcc to fold constants when using msecs_to_jiffies Date: Sun, 5 Apr 2015 09:23:55 +0200 Message-Id: <1428218636-3780-3-git-send-email-hofrat@osadl.org> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1428218636-3780-1-git-send-email-hofrat@osadl.org> References: <1428218636-3780-1-git-send-email-hofrat@osadl.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3923 Lines: 118 The majority of the msecs_to_jiffies() users in the kernel are passing in constants which would allow gcc to do constant folding by checking with __builtin_constant_p() in msecs_to_jiffies(). The original msecs_to_jiffies is renamed to __msecs_to_jiffies and aside from the removal of the check for negative values being moved out, is unaltered. Signed-off-by: Nicholas Mc Guire --- Thanks to Joe Perches for suggesting this approach and for his review comments on the first attempts. Patch was compile and boot tested (x86_64) and a few msecs_to_jiffies() locations verified by inspection of the .lst files. Patch is against 4.0-rc6 (localversion-next is -next-20150402) include/linux/jiffies.h | 29 ++++++++++++++++++++++++++++- kernel/time/time.c | 13 +++++-------- 2 files changed, 33 insertions(+), 9 deletions(-) diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h index c367cbd..dcd8ba5 100644 --- a/include/linux/jiffies.h +++ b/include/linux/jiffies.h @@ -7,6 +7,7 @@ #include #include #include /* for HZ */ +#include /* * The following defines establish the engineering parameters of the PLL @@ -288,7 +289,33 @@ static inline u64 jiffies_to_nsecs(const unsigned long j) return (u64)jiffies_to_usecs(j) * NSEC_PER_USEC; } -extern unsigned long msecs_to_jiffies(const unsigned int m); +extern unsigned long __msecs_to_jiffies(const unsigned int m); +static inline unsigned long msecs_to_jiffies(const unsigned int m) +{ + /* + * Negative value, means infinite timeout: + */ + if ((int)m < 0) + return MAX_JIFFY_OFFSET; + + if (__builtin_constant_p(m)) { +#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ) + return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ); +#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC) + if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET)) + return MAX_JIFFY_OFFSET; + return m * (HZ / MSEC_PER_SEC); +#else + if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET)) + return MAX_JIFFY_OFFSET; + + return (MSEC_TO_HZ_MUL32 * m + MSEC_TO_HZ_ADJ32) + >> MSEC_TO_HZ_SHR32; +#endif + } else + return __msecs_to_jiffies(m); +} + extern unsigned long usecs_to_jiffies(const unsigned int u); extern unsigned long timespec_to_jiffies(const struct timespec *value); extern void jiffies_to_timespec(const unsigned long jiffies, diff --git a/kernel/time/time.c b/kernel/time/time.c index 4fa1d26..3797540 100644 --- a/kernel/time/time.c +++ b/kernel/time/time.c @@ -488,6 +488,8 @@ EXPORT_SYMBOL(ns_to_timespec64); * the following way: * * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET) + * negative values are handled in msecs_to_jiffies in + * include/linux/jiffies.h * * - 'too large' values [that would result in larger than * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too. @@ -496,15 +498,10 @@ EXPORT_SYMBOL(ns_to_timespec64); * the input value by a factor or dividing it with a factor * * We must also be careful about 32-bit overflows. + * */ -unsigned long msecs_to_jiffies(const unsigned int m) +unsigned long __msecs_to_jiffies(const unsigned int m) { - /* - * Negative value, means infinite timeout: - */ - if ((int)m < 0) - return MAX_JIFFY_OFFSET; - #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ) /* * HZ is equal to or smaller than 1000, and 1000 is a nice @@ -537,7 +534,7 @@ unsigned long msecs_to_jiffies(const unsigned int m) >> MSEC_TO_HZ_SHR32; #endif } -EXPORT_SYMBOL(msecs_to_jiffies); +EXPORT_SYMBOL(__msecs_to_jiffies); unsigned long usecs_to_jiffies(const unsigned int u) { -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/