block: Make rq_affinity = 1 work as expected
Tao Ma [Fri, 5 Aug 2011 07:37:10 +0000 (09:37 +0200)]
Commit 5757a6d76c introduced a new rq_affinity = 2 so as to make
the request completed in the __make_request cpu. But it makes the
old rq_affinity = 1 not work any more. The root cause is that
if the 'cpu' and 'req->cpu' is in the same group and cpu != req->cpu,
ccpu will be the same as group_cpu, so the completion will be
excuted in the 'cpu' not 'group_cpu'.

This patch fix problem by simpling removing group_cpu and the codes
are more explicit now. If ccpu == cpu, we complete in cpu, otherwise
we raise_blk_irq to ccpu.

Cc: Christoph Hellwig <hch@infradead.org>
Cc: Roland Dreier <roland@purestorage.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Jens Axboe <jaxboe@fusionio.com>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Reviewed-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

block/blk-softirq.c

index 475fab8..487addc 100644 (file)
@@ -103,7 +103,7 @@ static struct notifier_block __cpuinitdata blk_cpu_notifier = {
 
 void __blk_complete_request(struct request *req)
 {
-       int ccpu, cpu, group_cpu = NR_CPUS;
+       int ccpu, cpu;
        struct request_queue *q = req->q;
        unsigned long flags;
 
@@ -117,14 +117,12 @@ 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 || ccpu == group_cpu) {
+       if (ccpu == cpu) {
                struct list_head *list;
 do_local:
                list = &__get_cpu_var(blk_cpu_done);