Re: Processes stuck on D state on Dual Opteron

[Nick Piggin]

Nick Piggin wrote:
Chen, Kenneth W wrote:

I like the patch a lot and already did bench it on our db setup.  
However,
I'm seeing a negative regression compare to a very very crappy patch (see
attached, you can laugh at me for doing things like that :-).

OK - if we go that way, perhaps the following patch may be the
way to do it.
Here.
--
SUSE Labs, Novell Inc.
Index: linux-2.6/drivers/block/ll_rw_blk.c
===================================================================
--- linux-2.6.orig/drivers/block/ll_rw_blk.c    2005-04-12 21:03:01.000000000 
+1000
+++ linux-2.6/drivers/block/ll_rw_blk.c 2005-04-12 21:03:45.000000000 +1000
@@ -1956,10 +1956,11 @@ out:
  */
 static struct request *get_request_wait(request_queue_t *q, int rw)
 {
-       DEFINE_WAIT(wait);
        struct request *rq;
 
-       do {
+       rq = get_request(q, rw, GFP_NOIO);
+       while (!rq) {
+               DEFINE_WAIT(wait);
                struct request_list *rl = &q->rq;
 
                prepare_to_wait_exclusive(&rl->wait[rw], &wait,
@@ -1987,7 +1988,7 @@ static struct request *get_request_wait(
                        spin_lock_irq(q->queue_lock);
                }
                finish_wait(&rl->wait[rw], &wait);
-       } while (!rq);
+       }
 
        return rq;
 }