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authorJens Axboe <axboe@kernel.dk>2011-10-19 14:30:42 +0200
committerJens Axboe <axboe@kernel.dk>2011-10-19 14:30:42 +0200
commit5c04b426f2e8b46cfc7969a35b2631063a3c646c (patch)
tree2d27d9f5d2fe5d5e8fbc01a467ec58bcb50235c1 /block/blk-softirq.c
parent499337bb6511e665a236a6a947f819d98ea340c6 (diff)
parent899e3ee404961a90b828ad527573aaaac39f0ab1 (diff)
Merge branch 'v3.1-rc10' into for-3.2/core
Conflicts: block/blk-core.c include/linux/blkdev.h Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-softirq.c')
-rw-r--r--block/blk-softirq.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/block/blk-softirq.c b/block/blk-softirq.c
index 475fab809a80..1366a89d8e66 100644
--- 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: