Christoph Lameter wrote:
isolate_page() currently uses an IPI to notify other processors that the lru
caches need to be drained if the page cannot be found on the LRU. The IPI
interrupt may interrupt a processor that is just processing lru requests
and cause a race condition.
This patch introduces a new function run_on_each_cpu() that uses the keventd()
to run the LRU draining on each processor. Processors disable preemption
when dealing the LRU caches (these are per processor) and thus executing
LRU draining from another process is safe.
Couple of comments:
===================================================================
--- linux-2.6.15-rc5-mm1.orig/kernel/workqueue.c 2005-12-05 11:15:24.000000000 -0800
+++ linux-2.6.15-rc5-mm1/kernel/workqueue.c 2005-12-06 17:50:44.000000000 -0800
@@ -424,6 +424,19 @@ int schedule_delayed_work_on(int cpu,
return ret;
}
+void schedule_on_each_cpu(void (*func) (void *info), void *info)
+{
+ int cpu;
+ struct work_struct * work = kmalloc(NR_CPUS * sizeof(struct work_struct), GFP_KERNEL);
+
Do we need a lock_cpu_hotplug() around here?
+ for_each_online_cpu(cpu) {
+ INIT_WORK(work + cpu, func, info);
+ __queue_work(per_cpu_ptr(keventd_wq->cpu_wq, cpu), work + cpu);
+ }
+ flush_workqueue(keventd_wq);
+ kfree(work);
+}
+
Can't this deadlock if 2 CPUs each send work to the other?
--
SUSE Labs, Novell Inc.
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