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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/02/2026 18.02, Eric Dumazet wrote: > For common cases (HZ=100, 250 or 1000), these helpers are > at most one multiply, 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 > --- > include/linux/jiffies.h | 40 ++++++++++++++++++++++++++++++++++++++-- > kernel/time/time.c | 19 +++++++------------ > 2 files changed, 45 insertions(+), 14 deletions(-) > > diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h > index fdef2c155c27202ae8ba910f170a62521294dc36..d1c3d4941854a82c4571032adb41ca57d5faa8bd 100644 > --- a/include/linux/jiffies.h > +++ b/include/linux/jiffies.h > @@ -434,8 +434,44 @@ 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); > + > +#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ) > +/** > + * jiffies_to_msecs - Convert jiffies to milliseconds > + * @j: jiffies value > + * > + * This inline version takes care of HZ in {100,250,1000}. > + * > + * Return: milliseconds value > + */ > +static inline unsigned int jiffies_to_msecs(const unsigned long j) > +{ > + return (MSEC_PER_SEC / HZ) * j; > +} > +#else > +unsigned int jiffies_to_msecs(const unsigned long j); > +#endif > + > +#if !(USEC_PER_SEC % HZ) > +/** > + * jiffies_to_usecs - Convert jiffies to microseconds > + * @j: jiffies value > + * > + * Return: microseconds value > + */ Hi Eric! This now causes warnings when doing "make htmldocs": .../Documentation/driver-api/basics:42: .../kernel/time/time.c:387: WARNING: Duplicate C declaration, also defined at driver-api/basics:436. Declaration is '.. c:function:: unsigned int jiffies_to_msecs (const unsigned long j)'. [duplicate_declaration.c] .../Documentation/driver-api/basics:42: .../kernel/time/time.c:410: WARNING: Duplicate C declaration, also defined at driver-api/basics:453. Declaration is '.. c:function:: unsigned int jiffies_to_usecs (const unsigned long j)'. [duplicate_declaration.c] Any ideas how to fix that best? Maybe the comments in the header should be just normal comments, and the kerneldoc should just reside in time.c ? Thanks, Thomas