bcache: Write out full stripes
Now that we're tracking dirty data per stripe, we can add two
optimizations for raid5/6:
* If a stripe is already dirty, force writes to that stripe to
writeback mode - to help build up full stripes of dirty data
* When flushing dirty data, preferentially write out full stripes first
if there are any.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index 017c95f..17bd597 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -22,8 +22,6 @@
#define CUTOFF_CACHE_ADD 95
#define CUTOFF_CACHE_READA 90
-#define CUTOFF_WRITEBACK 50
-#define CUTOFF_WRITEBACK_SYNC 75
struct kmem_cache *bch_search_cache;
@@ -998,17 +996,6 @@
cached_dev_bio_complete(cl);
}
-static bool should_writeback(struct cached_dev *dc, struct bio *bio)
-{
- unsigned threshold = (bio->bi_rw & REQ_SYNC)
- ? CUTOFF_WRITEBACK_SYNC
- : CUTOFF_WRITEBACK;
-
- return !atomic_read(&dc->disk.detaching) &&
- cache_mode(dc, bio) == CACHE_MODE_WRITEBACK &&
- dc->disk.c->gc_stats.in_use < threshold;
-}
-
static void request_write(struct cached_dev *dc, struct search *s)
{
struct closure *cl = &s->cl;
@@ -1030,12 +1017,16 @@
if (bio->bi_rw & REQ_DISCARD)
goto skip;
+ if (should_writeback(dc, s->orig_bio,
+ cache_mode(dc, bio),
+ s->op.skip)) {
+ s->op.skip = false;
+ s->writeback = true;
+ }
+
if (s->op.skip)
goto skip;
- if (should_writeback(dc, s->orig_bio))
- s->writeback = true;
-
trace_bcache_write(s->orig_bio, s->writeback, s->op.skip);
if (!s->writeback) {