From 7c13edc87510f665da3094174e1fd633e06649f4 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 18 Apr 2011 18:25:43 +1000 Subject: md: incorporate new plugging into raid5. In raid5 plugging is used for 2 things: 1/ collecting writes that require a bitmap update 2/ collecting writes in the hope that we can create full stripes - or at least more-full. We now release these different sets of stripes when plug_cnt is zero. Also in make_request, we call mddev_check_plug to hopefully increase plug_cnt, and wake up the thread at the end if plugging wasn't achieved for some reason. Signed-off-by: NeilBrown --- drivers/md/raid5.c | 23 ++++++++++++++++------- 1 file changed, 16 insertions(+), 7 deletions(-) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index a1755a6a3e5..f301e6ae220 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -27,12 +27,12 @@ * * We group bitmap updates into batches. Each batch has a number. * We may write out several batches at once, but that isn't very important. - * conf->bm_write is the number of the last batch successfully written. - * conf->bm_flush is the number of the last batch that was closed to + * conf->seq_write is the number of the last batch successfully written. + * conf->seq_flush is the number of the last batch that was closed to * new additions. * When we discover that we will need to write to any block in a stripe * (in add_stripe_bio) we update the in-memory bitmap and record in sh->bm_seq - * the number of the batch it will be in. This is bm_flush+1. + * the number of the batch it will be in. This is seq_flush+1. * When we are ready to do a write, if that batch hasn't been written yet, * we plug the array and queue the stripe for later. * When an unplug happens, we increment bm_flush, thus closing the current @@ -459,7 +459,7 @@ get_active_stripe(raid5_conf_t *conf, sector_t sector, < (conf->max_nr_stripes *3/4) || !conf->inactive_blocked), conf->device_lock, - md_wakeup_thread(conf->mddev->thread)); + ); conf->inactive_blocked = 0; } else init_stripe(sh, sector, previous); @@ -3927,6 +3927,7 @@ static int make_request(mddev_t *mddev, struct bio * bi) struct stripe_head *sh; const int rw = bio_data_dir(bi); int remaining; + int plugged; if (unlikely(bi->bi_rw & REQ_FLUSH)) { md_flush_request(mddev, bi); @@ -3945,6 +3946,7 @@ static int make_request(mddev_t *mddev, struct bio * bi) bi->bi_next = NULL; bi->bi_phys_segments = 1; /* over-loaded to count active stripes */ + plugged = mddev_check_plugged(mddev); for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) { DEFINE_WAIT(w); int disks, data_disks; @@ -4059,6 +4061,9 @@ static int make_request(mddev_t *mddev, struct bio * bi) } } + if (!plugged) + md_wakeup_thread(mddev->thread); + spin_lock_irq(&conf->device_lock); remaining = raid5_dec_bi_phys_segments(bi); spin_unlock_irq(&conf->device_lock); @@ -4472,14 +4477,18 @@ static void raid5d(mddev_t *mddev) while (1) { struct bio *bio; - if (conf->seq_flush != conf->seq_write) { - int seq = conf->seq_flush; + if (atomic_read(&mddev->plug_cnt) == 0 && + !list_empty(&conf->bitmap_list)) { + /* Now is a good time to flush some bitmap updates */ + conf->seq_flush++; spin_unlock_irq(&conf->device_lock); bitmap_unplug(mddev->bitmap); spin_lock_irq(&conf->device_lock); - conf->seq_write = seq; + conf->seq_write = conf->seq_flush; activate_bit_delay(conf); } + if (atomic_read(&mddev->plug_cnt) == 0) + raid5_activate_delayed(conf); while ((bio = remove_bio_from_retry(conf))) { int ok; -- cgit v1.2.3