The patch titled Use num_possible_cpus() instead of NR_CPUS for timer distribution has been added to the -mm tree. Its filename is use-num_possible_cpus-instead-of-nr_cpus-for-timer.patch *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find out what to do about this ------------------------------------------------------ Subject: Use num_possible_cpus() instead of NR_CPUS for timer distribution From: john stultz <johnstul@xxxxxxxxxx> To avoid lock contention, we distribute the sched_timer calls across the cpus so they do not trigger at the same instant. However, I used NR_CPUS, which can cause needless grouping on small smp systems depending on your kernel config. This patch converts to using num_possible_cpus() so we spread it as evenly as possible on every machine. Briefly tested w/ NR_CPUS=255 and verified reduced contention. Signed-off-by: John Stultz <johnstul@xxxxxxxxxx> Acked-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/time/tick-sched.c | 2 +- 1 files changed, 1 insertion(+), 1 deletion(-) diff -puN kernel/time/tick-sched.c~use-num_possible_cpus-instead-of-nr_cpus-for-timer kernel/time/tick-sched.c --- a/kernel/time/tick-sched.c~use-num_possible_cpus-instead-of-nr_cpus-for-timer +++ a/kernel/time/tick-sched.c @@ -574,7 +574,7 @@ void tick_setup_sched_timer(void) /* Get the next period (per cpu) */ ts->sched_timer.expires = tick_init_jiffy_update(); offset = ktime_to_ns(tick_period) >> 1; - do_div(offset, NR_CPUS); + do_div(offset, num_possible_cpus()); offset *= smp_processor_id(); ts->sched_timer.expires = ktime_add_ns(ts->sched_timer.expires, offset); _ Patches currently in -mm which might be from johnstul@xxxxxxxxxx are futex_unlock_pi-hurts-my-brain-and-may-cause.patch git-acpi.patch geode-mfgpt-clock-event-device-support.patch x86_64-hpet-restore-vread.patch x86_64-restore-restore-nohpet-cmdline.patch x86_64-prep-idle-loop-for-dynticks.patch x86_64-enable-high-resolution-timers-and-dynticks.patch x86_64-dynticks-disable-hpet_id_legsup-hpets.patch kernel-time-timekeepingc-cleanups.patch use-num_possible_cpus-instead-of-nr_cpus-for-timer.patch kernel-time-clocksourcec-use-list_for_each_entry-instead-of-list_for_each.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