aboutsummaryrefslogtreecommitdiffstats
path: root/block
diff options
context:
space:
mode:
Diffstat (limited to 'block')
-rw-r--r--block/blk-softirq.c16
1 files changed, 13 insertions, 3 deletions
diff --git a/block/blk-softirq.c b/block/blk-softirq.c
index 487addc85bb..58340d0cb23 100644
--- a/block/blk-softirq.c
+++ b/block/blk-softirq.c
@@ -103,7 +103,7 @@ static struct notifier_block __cpuinitdata blk_cpu_notifier = {
void __blk_complete_request(struct request *req)
{
- int ccpu, cpu;
+ int ccpu, cpu, group_cpu = NR_CPUS;
struct request_queue *q = req->q;
unsigned long flags;
@@ -117,12 +117,22 @@ void __blk_complete_request(struct request *req)
*/
if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) && req->cpu != -1) {
ccpu = req->cpu;
- if (!test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags))
+ if (!test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags)) {
ccpu = blk_cpu_to_group(ccpu);
+ group_cpu = blk_cpu_to_group(cpu);
+ }
} else
ccpu = cpu;
- if (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:
list = &__get_cpu_var(blk_cpu_done);