Messages in this thread Patch in this message | | | Subject | [patch 3/3]cfq-iosched: don't idle if a deep seek queue is slow | From | Shaohua Li <> | Date | Mon, 08 Nov 2010 10:07:25 +0800 |
| |
If a deep seek queue slowly deliver requests but disk is much faster, idle for the queue just wastes disk throughput. If the queue delevers all requests before half its slice is used, the patch disable idle for it. In my test, application delivers 32 requests one time, the disk can accept 128 requests at maxium and disk is fast. without the patch, the throughput is just around 30m/s, while with it, the speed is about 80m/s. The disk is a SSD, but is detected as a rotational disk. I can configure it as SSD, but I thought the deep seek queue logic should be fixed too, for example, considering a fast raid.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
--- block/cfq-iosched.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
Index: linux/block/cfq-iosched.c =================================================================== --- linux.orig/block/cfq-iosched.c 2010-11-08 08:43:51.000000000 +0800 +++ linux/block/cfq-iosched.c 2010-11-08 08:49:52.000000000 +0800 @@ -2293,6 +2293,17 @@ static struct cfq_queue *cfq_select_queu goto keep_queue; } + /* + * This is a deep seek queue, but the device is much faster than + * the queue can deliver, don't idle + **/ + if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) && + (cfq_cfqq_slice_new(cfqq) || + (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) { + cfq_clear_cfqq_deep(cfqq); + cfq_clear_cfqq_idle_window(cfqq); + } + if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { cfqq = NULL; goto keep_queue;
| |