* [PATCH linux-2.6.12-rc6-mm1] blk: elevator unplug thresh hanlding fix
@ 2005-06-16 3:47 Tejun Heo
2005-06-16 6:56 ` Jens Axboe
0 siblings, 1 reply; 2+ messages in thread
From: Tejun Heo @ 2005-06-16 3:47 UTC (permalink / raw)
To: axboe, akpm, linux-kernel
Hello, Jens.
Hello, Andrew.
This patch fixes q->unplug_thresh condition check in
__elv_add_request(). rq.count[READ] + rq.count[WRITE] can increase
more than one if another thread has allocated a request after the
current request is allocated or in_flight could have changed resulting
in larger-than-one change of nrq, thus breaking the threshold
mechanism.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Index: blk-fixes/drivers/block/elevator.c
===================================================================
--- blk-fixes.orig/drivers/block/elevator.c 2005-06-16 12:16:59.000000000 +0900
+++ blk-fixes/drivers/block/elevator.c 2005-06-16 12:17:03.000000000 +0900
@@ -352,7 +352,7 @@ void __elv_add_request(request_queue_t *
int nrq = q->rq.count[READ] + q->rq.count[WRITE]
- q->in_flight;
- if (nrq == q->unplug_thresh)
+ if (nrq >= q->unplug_thresh)
__generic_unplug_device(q);
}
} else
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2005-06-16 3:47 [PATCH linux-2.6.12-rc6-mm1] blk: elevator unplug thresh hanlding fix Tejun Heo
2005-06-16 6:56 ` Jens Axboe
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