From 316d315bffa4026f28085f6b24ebcebede370ac7 Mon Sep 17 00:00:00 2001 From: Nikanth Karthikesan Date: Tue, 6 Oct 2009 20:16:55 +0200 Subject: block: Seperate read and write statistics of in_flight requests v2 Commit a9327cac440be4d8333bba975cbbf76045096275 added seperate read and write statistics of in_flight requests. And exported the number of read and write requests in progress seperately through sysfs. But Corrado Zoccolo reported getting strange output from "iostat -kx 2". Global values for service time and utilization were garbage. For interval values, utilization was always 100%, and service time is higher than normal. So this was reverted by commit 0f78ab9899e9d6acb09d5465def618704255963b The problem was in part_round_stats_single(), I missed the following: if (now == part->stamp) return; - if (part->in_flight) { + if (part_in_flight(part)) { __part_stat_add(cpu, part, time_in_queue, part_in_flight(part) * (now - part->stamp)); __part_stat_add(cpu, part, io_ticks, (now - part->stamp)); With this chunk included, the reported regression gets fixed. Signed-off-by: Nikanth Karthikesan -- Signed-off-by: Jens Axboe --- drivers/md/dm.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) (limited to 'drivers') diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 23e76fe0d359..376f1ab48a24 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -130,7 +130,7 @@ struct mapped_device { /* * A list of ios that arrived while we were suspended. */ - atomic_t pending; + atomic_t pending[2]; wait_queue_head_t wait; struct work_struct work; struct bio_list deferred; @@ -453,13 +453,14 @@ static void start_io_acct(struct dm_io *io) { struct mapped_device *md = io->md; int cpu; + int rw = bio_data_dir(io->bio); io->start_time = jiffies; cpu = part_stat_lock(); part_round_stats(cpu, &dm_disk(md)->part0); part_stat_unlock(); - dm_disk(md)->part0.in_flight = atomic_inc_return(&md->pending); + dm_disk(md)->part0.in_flight[rw] = atomic_inc_return(&md->pending[rw]); } static void end_io_acct(struct dm_io *io) @@ -479,8 +480,9 @@ static void end_io_acct(struct dm_io *io) * After this is decremented the bio must not be touched if it is * a barrier. */ - dm_disk(md)->part0.in_flight = pending = - atomic_dec_return(&md->pending); + dm_disk(md)->part0.in_flight[rw] = pending = + atomic_dec_return(&md->pending[rw]); + pending += atomic_read(&md->pending[rw^0x1]); /* nudge anyone waiting on suspend queue */ if (!pending) @@ -1785,7 +1787,8 @@ static struct mapped_device *alloc_dev(int minor) if (!md->disk) goto bad_disk; - atomic_set(&md->pending, 0); + atomic_set(&md->pending[0], 0); + atomic_set(&md->pending[1], 0); init_waitqueue_head(&md->wait); INIT_WORK(&md->work, dm_wq_work); init_waitqueue_head(&md->eventq); @@ -2088,7 +2091,8 @@ static int dm_wait_for_completion(struct mapped_device *md, int interruptible) break; } spin_unlock_irqrestore(q->queue_lock, flags); - } else if (!atomic_read(&md->pending)) + } else if (!atomic_read(&md->pending[0]) && + !atomic_read(&md->pending[1])) break; if (interruptible == TASK_INTERRUPTIBLE && -- cgit v1.2.2