diff options
| author | Eric Dumazet <edumazet@google.com> | 2026-02-10 17:02:25 +0000 |
|---|---|---|
| committer | Thomas Gleixner <tglx@kernel.org> | 2026-02-11 08:55:52 +0100 |
| commit | b777b5e09eabeefc6ba80f4296366a4742701103 (patch) | |
| tree | 44b7fc4cdaae5fc8cd061655d70bce96bc163759 /kernel | |
| parent | 192c0159402e6bfbe13de6f8379546943297783d (diff) | |
time/jiffies: Inline jiffies_to_msecs() and jiffies_to_usecs()
For common cases (HZ=100, 250 or 1000), these helpers are at most one
multiply, so there is no point calling a tiny function.
Keep them out of line for HZ=300 and others.
This saves cycles in TCP fast path, among other things.
$ scripts/bloat-o-meter -t vmlinux.old vmlinux.new
add/remove: 0/8 grow/shrink: 25/89 up/down: 530/-3474 (-2944)
...
nla_put_msecs 193 - -193
message_stats_print 2131 920 -1211
Total: Before=25365208, After=25362264, chg -0.01%
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260210170226.57209-1-edumazet@google.com
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/time/time.c | 19 |
1 files changed, 7 insertions, 12 deletions
diff --git a/kernel/time/time.c b/kernel/time/time.c index 0ba8e3c50d62..36fd2313ae7e 100644 --- a/kernel/time/time.c +++ b/kernel/time/time.c @@ -365,20 +365,16 @@ SYSCALL_DEFINE1(adjtimex_time32, struct old_timex32 __user *, utp) } #endif +#if HZ > MSEC_PER_SEC || (MSEC_PER_SEC % HZ) /** * jiffies_to_msecs - Convert jiffies to milliseconds * @j: jiffies value * - * Avoid unnecessary multiplications/divisions in the - * two most common HZ cases. - * * Return: milliseconds value */ 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) +#if 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 @@ -390,7 +386,9 @@ unsigned int jiffies_to_msecs(const unsigned long j) #endif } EXPORT_SYMBOL(jiffies_to_msecs); +#endif +#if (USEC_PER_SEC % HZ) /** * jiffies_to_usecs - Convert jiffies to microseconds * @j: jiffies value @@ -405,17 +403,14 @@ unsigned int jiffies_to_usecs(const unsigned long j) */ BUILD_BUG_ON(HZ > USEC_PER_SEC); -#if !(USEC_PER_SEC % HZ) - return (USEC_PER_SEC / HZ) * j; -#else -# if BITS_PER_LONG == 32 +#if BITS_PER_LONG == 32 return (HZ_TO_USEC_MUL32 * j) >> HZ_TO_USEC_SHR32; -# else +#else return (j * HZ_TO_USEC_NUM) / HZ_TO_USEC_DEN; -# endif #endif } EXPORT_SYMBOL(jiffies_to_usecs); +#endif /** * mktime64 - Converts date to seconds. |