From 84890c03b6c5d7e8d76ea5e20b6aaf7e7ad410f0 Mon Sep 17 00:00:00 2001 From: Shaohua Li Date: Wed, 15 Feb 2017 19:58:05 -0800 Subject: [PATCH] md/raid5-cache: bump flush stripe batch size Bump the flush stripe batch size to 2048. For my 12 disks raid array, the stripes takes: 12 * 4k * 2048 = 96MB This is still quite small. A hardware raid card generally has 1GB size, which we suggest the raid5-cache has similar cache size. The advantage of a big batch size is we can dispatch a lot of IO in the same time, then we can do some scheduling to make better IO pattern. Last patch prioritizes stripes, so we don't worry about a big flush stripe batch will starve normal stripes. Signed-off-by: Shaohua Li --- drivers/md/raid5-cache.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c index 3f307be01b10..738e180d3740 100644 --- a/drivers/md/raid5-cache.c +++ b/drivers/md/raid5-cache.c @@ -43,7 +43,7 @@ /* wake up reclaim thread periodically */ #define R5C_RECLAIM_WAKEUP_INTERVAL (30 * HZ) /* start flush with these full stripes */ -#define R5C_FULL_STRIPE_FLUSH_BATCH 256 +#define R5C_FULL_STRIPE_FLUSH_BATCH(conf) (conf->max_nr_stripes / 4) /* reclaim stripes in groups */ #define R5C_RECLAIM_STRIPE_GROUP (NR_STRIPE_HASH_LOCKS * 2) @@ -381,7 +381,7 @@ void r5c_check_cached_full_stripe(struct r5conf *conf) * or a full stripe (chunk size / 4k stripes). */ if (atomic_read(&conf->r5c_cached_full_stripes) >= - min(R5C_FULL_STRIPE_FLUSH_BATCH, + min(R5C_FULL_STRIPE_FLUSH_BATCH(conf), conf->chunk_sectors >> STRIPE_SHIFT)) r5l_wake_reclaim(conf->log, 0); } @@ -1393,7 +1393,7 @@ static void r5c_do_reclaim(struct r5conf *conf) stripes_to_flush = R5C_RECLAIM_STRIPE_GROUP; else if (total_cached > conf->min_nr_stripes * 1 / 2 || atomic_read(&conf->r5c_cached_full_stripes) - flushing_full > - R5C_FULL_STRIPE_FLUSH_BATCH) + R5C_FULL_STRIPE_FLUSH_BATCH(conf)) /* * if stripe cache pressure moderate, or if there is many full * stripes,flush all full stripes -- GitLab