Merge branch 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git...

[pandora-kernel.git] / block / blk-softirq.c

diff --git a/block/blk-softirq.c b/block/blk-softirq.c
index 475fab8..1366a89 100644 (file)
--- a/block/blk-softirq.c
+++ b/block/blk-softirq.c
@@ -115,7 +115,7 @@ void __blk_complete_request(struct request *req)
        /*
         * Select completion CPU
         */
-       if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) && req->cpu != -1) {
+       if (req->cpu != -1) {
                ccpu = req->cpu;
                if (!test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags)) {
                        ccpu = blk_cpu_to_group(ccpu);
@@ -124,6 +124,14 @@ void __blk_complete_request(struct request *req)
        } else
                ccpu = cpu;
 
+       /*
+        * If current CPU and requested CPU are in the same group, running
+        * softirq in current CPU. One might concern this is just like
+        * QUEUE_FLAG_SAME_FORCE, but actually not. blk_complete_request() is
+        * running in interrupt handler, and currently I/O controller doesn't
+        * support multiple interrupts, so current CPU is unique actually. This
+        * avoids IPI sending from current CPU to the first CPU of a group.
+        */
        if (ccpu == cpu || ccpu == group_cpu) {
                struct list_head *list;
 do_local: