[lkml]   [2005]   [Mar]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[patch] use cheaper elv_queue_empty when unplug a device
This patch was posted last year and if I remember correctly, Jens said
he is OK with the patch. In function __generic_unplug_deivce(), kernel
can use a cheaper function elv_queue_empty() instead of more expensive
elv_next_request to find whether the queue is empty or not. blk_run_queue
can also made conditional on whether queue's emptiness before calling

Signed-off-by: Ken Chen <>

--- linux-2.6.11/drivers/block/ll_rw_blk.c.orig 2005-03-28 18:22:26.000000000 -0800
+++ linux-2.6.11/drivers/block/ll_rw_blk.c 2005-03-28 18:44:46.000000000 -0800
@@ -1459,7 +1459,7 @@ void __generic_unplug_device(request_que
* was plugged, fire request_fn if queue has stuff to do
- if (elv_next_request(q))
+ if (!elv_queue_empty(q))
@@ -1589,7 +1589,8 @@ void blk_run_queue(struct request_queue

spin_lock_irqsave(q->queue_lock, flags);
- q->request_fn(q);
+ if (!elv_queue_empty(q))
+ q->request_fn(q);
spin_unlock_irqrestore(q->queue_lock, flags);

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-04-06 13:31    [W:0.089 / U:0.328 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site