[dm-devel] [for-3.19 PATCH v2 06/17] dm thin: prefetch missing metadata pages
Mike Snitzer
snitzer at redhat.com
Fri Oct 17 18:37:08 UTC 2014
From: Joe Thornber <ejt at redhat.com>
Prefetch metadata at the start of the worker thread and then again every
128th bio processed from the deferred list.
Signed-off-by: Joe Thornber <ejt at redhat.com>
Signed-off-by: Mike Snitzer <snitzer at redhat.com>
---
drivers/md/dm-thin-metadata.c | 5 +++++
drivers/md/dm-thin-metadata.h | 5 +++++
drivers/md/dm-thin.c | 10 ++++++----
3 files changed, 16 insertions(+), 4 deletions(-)
diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c
index ee42d1c..43adbb8 100644
--- a/drivers/md/dm-thin-metadata.c
+++ b/drivers/md/dm-thin-metadata.c
@@ -1809,3 +1809,8 @@ bool dm_pool_metadata_needs_check(struct dm_pool_metadata *pmd)
return needs_check;
}
+
+void dm_pool_issue_prefetches(struct dm_pool_metadata *pmd)
+{
+ dm_tm_issue_prefetches(pmd->tm);
+}
diff --git a/drivers/md/dm-thin-metadata.h b/drivers/md/dm-thin-metadata.h
index efedd5a..921d15e 100644
--- a/drivers/md/dm-thin-metadata.h
+++ b/drivers/md/dm-thin-metadata.h
@@ -213,6 +213,11 @@ int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd,
int dm_pool_metadata_set_needs_check(struct dm_pool_metadata *pmd);
bool dm_pool_metadata_needs_check(struct dm_pool_metadata *pmd);
+/*
+ * Issue any prefetches that may be useful.
+ */
+void dm_pool_issue_prefetches(struct dm_pool_metadata *pmd);
+
/*----------------------------------------------------------------*/
#endif
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 2459628..1d25b51 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -1526,6 +1526,7 @@ static void process_thin_deferred_bios(struct thin_c *tc)
struct bio *bio;
struct bio_list bios;
struct blk_plug plug;
+ unsigned count = 0;
if (tc->requeue_mode) {
requeue_bio_list(tc, &tc->deferred_bio_list);
@@ -1567,6 +1568,10 @@ static void process_thin_deferred_bios(struct thin_c *tc)
pool->process_discard(tc, bio);
else
pool->process_bio(tc, bio);
+
+ if ((count++ & 127) == 0) {
+ dm_pool_issue_prefetches(pool->pmd);
+ }
}
blk_finish_plug(&plug);
}
@@ -1652,6 +1657,7 @@ static void do_worker(struct work_struct *ws)
{
struct pool *pool = container_of(ws, struct pool, worker);
+ dm_pool_issue_prefetches(pool->pmd);
process_prepared(pool, &pool->prepared_mappings, &pool->process_prepared_mapping);
process_prepared(pool, &pool->prepared_discards, &pool->process_prepared_discard);
process_deferred_bios(pool);
@@ -1990,10 +1996,6 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio)
/* fall through */
case -EWOULDBLOCK:
- /*
- * In future, the failed dm_thin_find_block above could
- * provide the hint to load the metadata into cache.
- */
thin_defer_bio(tc, bio);
return DM_MAPIO_SUBMITTED;
--
1.8.3.1
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