The patch titled Subject: cpumask: avoid mask based num_possible_cpus() and num_online_cpus() has been removed from the -mm tree. Its filename was cpumask-avoid-mask-based-num_possible_cpus-and-num_online_cpus.patch This patch was dropped because it had testing failures The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ From: Venkatesh Pallipadi <venki@xxxxxxxxxx> Subject: cpumask: avoid mask based num_possible_cpus() and num_online_cpus() The kernel's notion of possible cpus (from include/linux/cpumask.h) is * cpu_possible_mask- has bit 'cpu' set iff cpu is populatable * The cpu_possible_mask is fixed at boot time, as the set of CPU id's * that it is possible might ever be plugged in at anytime during the * life of that system boot. #define num_possible_cpus() cpumask_weight(cpu_possible_mask) and on x86 cpumask_weight() calls hweight64 and hweight64 (on older kernels and systems with !X86_FEATURE_POPCNT) or a popcnt based alternative. i.e, We needlessly go through this mask based calculation everytime num_possible_cpus() is called. The problem is there with cpu_online_mask() as well, which is a fixed value at boot time in !CONFIG_HOTPLUG_CPU case and should not change that often even in HOTPLUG case. Though most of the callers of these two routines are at init time (with only a few runtime calls), it is cleaner to use variables and not go through this repeated mask based calculation. Signed-off-by: Venkatesh Pallipadi <venki@xxxxxxxxxx> Acked-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx> Acked-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/cpumask.h | 9 +++++++-- kernel/cpu.c | 13 +++++++++++++ 2 files changed, 20 insertions(+), 2 deletions(-) diff -puN include/linux/cpumask.h~cpumask-avoid-mask-based-num_possible_cpus-and-num_online_cpus include/linux/cpumask.h --- a/include/linux/cpumask.h~cpumask-avoid-mask-based-num_possible_cpus-and-num_online_cpus +++ a/include/linux/cpumask.h @@ -27,6 +27,9 @@ typedef struct cpumask { DECLARE_BITMAP( extern int nr_cpu_ids; #endif +extern unsigned int nr_online_cpus; +extern unsigned int nr_possible_cpus; + #ifdef CONFIG_CPUMASK_OFFSTACK /* Assuming NR_CPUS is huge, a runtime limit is more efficient. Also, * not all bits may be allocated. */ @@ -81,8 +84,10 @@ extern const struct cpumask *const cpu_p extern const struct cpumask *const cpu_active_mask; #if NR_CPUS > 1 -#define num_online_cpus() cpumask_weight(cpu_online_mask) -#define num_possible_cpus() cpumask_weight(cpu_possible_mask) + +#define num_online_cpus() (nr_online_cpus) +#define num_possible_cpus() (nr_possible_cpus) + #define num_present_cpus() cpumask_weight(cpu_present_mask) #define num_active_cpus() cpumask_weight(cpu_active_mask) #define cpu_online(cpu) cpumask_test_cpu((cpu), cpu_online_mask) diff -puN kernel/cpu.c~cpumask-avoid-mask-based-num_possible_cpus-and-num_online_cpus kernel/cpu.c --- a/kernel/cpu.c~cpumask-avoid-mask-based-num_possible_cpus-and-num_online_cpus +++ a/kernel/cpu.c @@ -604,9 +604,13 @@ EXPORT_SYMBOL(cpu_all_bits); #ifdef CONFIG_INIT_ALL_POSSIBLE static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly = CPU_BITS_ALL; +unsigned int nr_possible_cpus __read_mostly = CONFIG_NR_CPUS; #else static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly; +unsigned int nr_possible_cpus __read_mostly; #endif +EXPORT_SYMBOL(nr_possible_cpus); + const struct cpumask *const cpu_possible_mask = to_cpumask(cpu_possible_bits); EXPORT_SYMBOL(cpu_possible_mask); @@ -614,6 +618,9 @@ static DECLARE_BITMAP(cpu_online_bits, C const struct cpumask *const cpu_online_mask = to_cpumask(cpu_online_bits); EXPORT_SYMBOL(cpu_online_mask); +unsigned int nr_online_cpus __read_mostly; +EXPORT_SYMBOL(nr_online_cpus); + static DECLARE_BITMAP(cpu_present_bits, CONFIG_NR_CPUS) __read_mostly; const struct cpumask *const cpu_present_mask = to_cpumask(cpu_present_bits); EXPORT_SYMBOL(cpu_present_mask); @@ -628,6 +635,8 @@ void set_cpu_possible(unsigned int cpu, cpumask_set_cpu(cpu, to_cpumask(cpu_possible_bits)); else cpumask_clear_cpu(cpu, to_cpumask(cpu_possible_bits)); + + nr_possible_cpus = cpumask_weight(cpu_possible_mask); } void set_cpu_present(unsigned int cpu, bool present) @@ -644,6 +653,8 @@ void set_cpu_online(unsigned int cpu, bo cpumask_set_cpu(cpu, to_cpumask(cpu_online_bits)); else cpumask_clear_cpu(cpu, to_cpumask(cpu_online_bits)); + + nr_online_cpus = cpumask_weight(cpu_online_mask); } void set_cpu_active(unsigned int cpu, bool active) @@ -662,9 +673,11 @@ void init_cpu_present(const struct cpuma void init_cpu_possible(const struct cpumask *src) { cpumask_copy(to_cpumask(cpu_possible_bits), src); + nr_possible_cpus = cpumask_weight(cpu_possible_mask); } void init_cpu_online(const struct cpumask *src) { cpumask_copy(to_cpumask(cpu_online_bits), src); + nr_online_cpus = cpumask_weight(cpu_online_mask); } _ Patches currently in -mm which might be from venki@xxxxxxxxxx are linux-next.patch lib-cpumaskc-remove-__any_online_cpu.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