From: Andrew Morton schedule_on_each_cpu() presently does a large kmalloc - 96 kbytes on 1024 CPU 64-bit. Rework it so that we do one 8192-byte allocation and then a pile of tiny ones, via alloc_percpu(). This has a much higher chance of success (100% in the current VM). This also has the effect of reducing the memory requirements from NR_CPUS*n to num_possible_cpus()*n. Cc: Christoph Lameter Cc: Andi Kleen Signed-off-by: Andrew Morton --- kernel/workqueue.c | 28 ++++++++++++++++++++-------- 1 files changed, 20 insertions(+), 8 deletions(-) diff -puN kernel/workqueue.c~schedule_on_each_cpu-reduce-kmalloc-size kernel/workqueue.c --- devel/kernel/workqueue.c~schedule_on_each_cpu-reduce-kmalloc-size 2006-05-22 15:07:56.000000000 -0700 +++ devel-akpm/kernel/workqueue.c 2006-05-22 16:26:54.000000000 -0700 @@ -428,22 +428,34 @@ int schedule_delayed_work_on(int cpu, return ret; } -int schedule_on_each_cpu(void (*func) (void *info), void *info) +/** + * schedule_on_each_cpu - call a function on each online CPU from keventd + * @func: the function to call + * @info: a pointer to pass to func() + * + * Returns zero on success. + * Returns -ve errno on failure. + * + * Appears to be racy against CPU hotplug. + * + * schedule_on_each_cpu() is very slow. + */ +int schedule_on_each_cpu(void (*func)(void *info), void *info) { int cpu; - struct work_struct *work; + struct work_struct *works; - work = kmalloc(NR_CPUS * sizeof(struct work_struct), GFP_KERNEL); - - if (!work) + works = alloc_percpu(struct work_struct); + if (!works) return -ENOMEM; + for_each_online_cpu(cpu) { - INIT_WORK(work + cpu, func, info); + INIT_WORK(per_cpu_ptr(works, cpu), func, info); __queue_work(per_cpu_ptr(keventd_wq->cpu_wq, cpu), - work + cpu); + per_cpu_ptr(works, cpu)); } flush_workqueue(keventd_wq); - kfree(work); + free_percpu(works); return 0; } _