The patch titled Subject: jiffies conversions: Use compile time constants when possible has been added to the -mm tree. Its filename is jiffies-conversions-use-compile-time-constants-when-possible.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Joe Perches <joe@xxxxxxxxxxx> Subject: jiffies conversions: Use compile time constants when possible Do the multiplications and divisions at compile time instead of runtime when the converted value is a constant. Make the calculation functions static __always_inline to jiffies.h. Add #defines with __builtin_constant_p to test and use the static inline or the runtime functions as appropriate. Prefix the old exported symbols/functions with __ (akpm: shaves 100 bytes from my allnoconfig vmlinux .text) Signed-off-by: Joe Perches <joe@xxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Kent Overstreet <koverstreet@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/jiffies.h | 136 ++++++++++++++++++++++++++++++++++++-- kernel/time.c | 106 +++-------------------------- 2 files changed, 144 insertions(+), 98 deletions(-) diff -puN include/linux/jiffies.h~jiffies-conversions-use-compile-time-constants-when-possible include/linux/jiffies.h --- a/include/linux/jiffies.h~jiffies-conversions-use-compile-time-constants-when-possible +++ a/include/linux/jiffies.h @@ -289,10 +289,138 @@ extern unsigned long preset_lpj; /* * Convert various time units to each other: */ -extern unsigned int jiffies_to_msecs(const unsigned long j); -extern unsigned int jiffies_to_usecs(const unsigned long j); -extern unsigned long msecs_to_jiffies(const unsigned int m); -extern unsigned long usecs_to_jiffies(const unsigned int u); + +/* + * Avoid unnecessary multiplications/divisions in the + * two most common HZ cases: + */ +static __always_inline unsigned int +__inline_jiffies_to_msecs(const unsigned long j) +{ +#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ) + return (MSEC_PER_SEC / HZ) * j; +#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC) + return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC); +#else +# if BITS_PER_LONG == 32 + return (HZ_TO_MSEC_MUL32 * j) >> HZ_TO_MSEC_SHR32; +# else + return (j * HZ_TO_MSEC_NUM) / HZ_TO_MSEC_DEN; +# endif +#endif +} +extern unsigned int __jiffies_to_msecs(const unsigned long j); + +#define jiffies_to_msecs(x) \ + (__builtin_constant_p(x) ? \ + __inline_jiffies_to_msecs(x) : \ + __jiffies_to_msecs(x)) + +static __always_inline unsigned int +__inline_jiffies_to_usecs(const unsigned long j) +{ +#if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ) + return (USEC_PER_SEC / HZ) * j; +#elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC) + return (j + (HZ / USEC_PER_SEC) - 1)/(HZ / USEC_PER_SEC); +#else +# if BITS_PER_LONG == 32 + return (HZ_TO_USEC_MUL32 * j) >> HZ_TO_USEC_SHR32; +# else + return (j * HZ_TO_USEC_NUM) / HZ_TO_USEC_DEN; +# endif +#endif +} +extern unsigned int __jiffies_to_usecs(const unsigned long j); + +#define jiffies_to_usecs(x) \ + (__builtin_constant_p(x) ? \ + __inline_jiffies_to_usecs(x) : \ + __jiffies_to_usecs(x)) + +/* + * When we convert to jiffies then we interpret incoming values + * the following way: + * + * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET) + * + * - 'too large' values [that would result in larger than + * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too. + * + * - all other values are converted to jiffies by either multiplying + * the input value by a factor or dividing it with a factor + * + * We must also be careful about 32-bit overflows. + */ +static __always_inline unsigned long +__inline_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 + * round multiple of HZ, divide with the factor between them, + * but round upwards: + */ + return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ); +#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC) + /* + * HZ is larger than 1000, and HZ is a nice round multiple of + * 1000 - simply multiply with the factor between them. + * + * But first make sure the multiplication result cannot + * overflow: + */ + if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET)) + return MAX_JIFFY_OFFSET; + + return m * (HZ / MSEC_PER_SEC); +#else + /* + * Generic case - multiply, round and divide. But first + * check that if we are doing a net multiplication, that + * we wouldn't overflow: + */ + 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 +} +extern unsigned long __msecs_to_jiffies(const unsigned int m); + +#define msecs_to_jiffies(x) \ + (__builtin_constant_p(x) ? \ + __inline_msecs_to_jiffies(x) : \ + __msecs_to_jiffies(x)) + +static __always_inline unsigned long +__inline_usecs_to_jiffies(const unsigned int u) +{ + if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET)) + return MAX_JIFFY_OFFSET; +#if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ) + return (u + (USEC_PER_SEC / HZ) - 1) / (USEC_PER_SEC / HZ); +#elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC) + return u * (HZ / USEC_PER_SEC); +#else + return (USEC_TO_HZ_MUL32 * u + USEC_TO_HZ_ADJ32) + >> USEC_TO_HZ_SHR32; +#endif +} +extern unsigned long __usecs_to_jiffies(const unsigned int u); + +#define usecs_to_jiffies(x) \ + (__builtin_constant_p(x) ? \ + __inline_usecs_to_jiffies(x) : \ + __usecs_to_jiffies(x)) + extern unsigned long timespec_to_jiffies(const struct timespec *value); extern void jiffies_to_timespec(const unsigned long jiffies, struct timespec *value); diff -puN kernel/time.c~jiffies-conversions-use-compile-time-constants-when-possible kernel/time.c --- a/kernel/time.c~jiffies-conversions-use-compile-time-constants-when-possible +++ a/kernel/time.c @@ -228,41 +228,18 @@ EXPORT_SYMBOL(current_fs_time); /* * Convert jiffies to milliseconds and back. - * - * Avoid unnecessary multiplications/divisions in the - * two most common HZ cases: */ -inline unsigned int jiffies_to_msecs(const unsigned long j) +unsigned int __jiffies_to_msecs(const unsigned long j) { -#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ) - return (MSEC_PER_SEC / HZ) * j; -#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC) - return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC); -#else -# if BITS_PER_LONG == 32 - return (HZ_TO_MSEC_MUL32 * j) >> HZ_TO_MSEC_SHR32; -# else - return (j * HZ_TO_MSEC_NUM) / HZ_TO_MSEC_DEN; -# endif -#endif + return __inline_jiffies_to_msecs(j); } -EXPORT_SYMBOL(jiffies_to_msecs); +EXPORT_SYMBOL(__jiffies_to_msecs); -inline unsigned int jiffies_to_usecs(const unsigned long j) +unsigned int __jiffies_to_usecs(const unsigned long j) { -#if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ) - return (USEC_PER_SEC / HZ) * j; -#elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC) - return (j + (HZ / USEC_PER_SEC) - 1)/(HZ / USEC_PER_SEC); -#else -# if BITS_PER_LONG == 32 - return (HZ_TO_USEC_MUL32 * j) >> HZ_TO_USEC_SHR32; -# else - return (j * HZ_TO_USEC_NUM) / HZ_TO_USEC_DEN; -# endif -#endif + return __inline_jiffies_to_usecs(j); } -EXPORT_SYMBOL(jiffies_to_usecs); +EXPORT_SYMBOL(__jiffies_to_usecs); /** * timespec_trunc - Truncate timespec to a granularity @@ -411,76 +388,17 @@ struct timeval ns_to_timeval(const s64 n } EXPORT_SYMBOL(ns_to_timeval); -/* - * When we convert to jiffies then we interpret incoming values - * the following way: - * - * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET) - * - * - 'too large' values [that would result in larger than - * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too. - * - * - all other values are converted to jiffies by either multiplying - * 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 - * round multiple of HZ, divide with the factor between them, - * but round upwards: - */ - return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ); -#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC) - /* - * HZ is larger than 1000, and HZ is a nice round multiple of - * 1000 - simply multiply with the factor between them. - * - * But first make sure the multiplication result cannot - * overflow: - */ - if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET)) - return MAX_JIFFY_OFFSET; - - return m * (HZ / MSEC_PER_SEC); -#else - /* - * Generic case - multiply, round and divide. But first - * check that if we are doing a net multiplication, that - * we wouldn't overflow: - */ - 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 + return __inline_msecs_to_jiffies(m); } -EXPORT_SYMBOL(msecs_to_jiffies); +EXPORT_SYMBOL(__msecs_to_jiffies); -unsigned long usecs_to_jiffies(const unsigned int u) +unsigned long __usecs_to_jiffies(const unsigned int u) { - if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET)) - return MAX_JIFFY_OFFSET; -#if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ) - return (u + (USEC_PER_SEC / HZ) - 1) / (USEC_PER_SEC / HZ); -#elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC) - return u * (HZ / USEC_PER_SEC); -#else - return (USEC_TO_HZ_MUL32 * u + USEC_TO_HZ_ADJ32) - >> USEC_TO_HZ_SHR32; -#endif + return __inline_usecs_to_jiffies(u); } -EXPORT_SYMBOL(usecs_to_jiffies); +EXPORT_SYMBOL(__usecs_to_jiffies); /* * The TICK_NSEC - 1 rounds up the value to the next resolution. Note _ Patches currently in -mm which might be from joe@xxxxxxxxxxx are origin.patch linux-next.patch compiler-gcc4h-reorder-macros-based-upon-gcc-ver.patch compiler-gcch-add-gcc-recommended-gcc_version-macro.patch compiler-gcc34h-use-gcc_version-macro.patch compiler-gcc4h-bugh-remove-duplicate-macros.patch bugh-fix-build_bug_on-macro-in-__checker__.patch bugh-prevent-double-evaulation-of-in-build_bug_on.patch bugh-make-build_bug_on-generate-compile-time-error.patch compilerh-bugh-prevent-double-error-messages-with-build_bug_on.patch bugh-compilerh-introduce-compiletime_assert-build_bug_on_msg.patch jiffies-conversions-use-compile-time-constants-when-possible.patch get_maintainerpl-find-maintainers-for-removed-files.patch checkpatch-prefer-dev_level-to-dev_printkkern_level.patch checkpatch-warn-on-unnecessary-__devfoo-section-markings.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html