Messages in this thread Patch in this message | | | From | "Chen, Kenneth W" <> | Subject | [patch] use cheaper elv_queue_empty when unplug a device | Date | Mon, 28 Mar 2005 18:53:49 -0800 |
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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 request_fn().
Signed-off-by: Ken Chen <kenneth.w.chen@intel.com>
--- 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)) q->request_fn(q); } EXPORT_SYMBOL(__generic_unplug_device); @@ -1589,7 +1589,8 @@ void blk_run_queue(struct request_queue
spin_lock_irqsave(q->queue_lock, flags); blk_remove_plug(q); - q->request_fn(q); + if (!elv_queue_empty(q)) + q->request_fn(q); spin_unlock_irqrestore(q->queue_lock, flags); } EXPORT_SYMBOL(blk_run_queue);
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