From: Tang Junhui <tang.junhui@xxxxxxxxxx>
Since no new bucket can be allocated during GC, and front side I/Os would
run out of all the buckets, so notify allocator to pack the free_inc queue
full of buckets before GC, then we could have enough buckets for front side
I/Os during GC period.
Signed-off-by: Tang Junhui <tang.junhui@xxxxxxxxxx>
---
drivers/md/bcache/alloc.c | 11 +++++++-
drivers/md/bcache/bcache.h | 2 ++
drivers/md/bcache/btree.c | 69 ++++++++++++++++++++++++++++++++++++++++++++--
drivers/md/bcache/btree.h | 4 +++
4 files changed, 83 insertions(+), 3 deletions(-)
diff --git a/drivers/md/bcache/alloc.c b/drivers/md/bcache/alloc.c
index a0cc1bc..85020cc 100644
--- a/drivers/md/bcache/alloc.c
+++ b/drivers/md/bcache/alloc.c
@@ -323,7 +323,8 @@ static int bch_allocator_thread(void *arg)
* possibly issue discards to them, then we add the bucket to
* the free list:
*/
- while (!fifo_empty(&ca->free_inc)) {
+ while (!fifo_empty(&ca->free_inc) &&
+ ca->prepare_gc != GC_PREPARING) {
long bucket;
fifo_pop(&ca->free_inc, bucket);
@@ -353,6 +354,14 @@ static int bch_allocator_thread(void *arg)
invalidate_buckets(ca);
/*
+ * Let GC continue
+ */
+ if (ca->prepare_gc == GC_PREPARING) {
+ ca->prepare_gc = GC_PREPARED;
+ wake_up_gc(ca->set);
+ }
+
+ /*
* Now, we write their new gens to disk so we can start writing
* new stuff to them:
*/
diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index ab4c9ca..61a6ff2 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -428,6 +428,8 @@ struct cache {
* cpu
*/
unsigned invalidate_needs_gc;
+ /* used to notify allocator to prepare GC*/
+ unsigned int prepare_gc;
bool discard; /* Get rid of? */
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 10f967e..aba0700 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -1805,6 +1805,46 @@ static void bch_btree_gc(struct cache_set *c)
bch_moving_gc(c);
}
+static bool cache_gc_prepare_none(struct cache_set *c)
+{
+ struct cache *ca;
+ unsigned int i;
+
+ for_each_cache(ca, c, i)
+ if (ca->prepare_gc != GC_PREPARE_NONE)
+ return false;
+ return true;
+}
+
+static bool cache_gc_prepare_ok(struct cache_set *c)
+{
+ struct cache *ca;
+ unsigned int i;
+
+ for_each_cache(ca, c, i)
+ if (ca->prepare_gc != GC_PREPARED)
+ return false;
+ return true;
+}
+
+static void set_cache_gc_prepare_none(struct cache_set *c)
+{
+ struct cache *ca;
+ unsigned int i;
+
+ for_each_cache(ca, c, i)
+ ca->prepare_gc = GC_PREPARE_NONE;
+}
+
+static void set_cache_gc_preparing(struct cache_set *c)
+{
+ struct cache *ca;
+ unsigned int i;
+
+ for_each_cache(ca, c, i)
+ ca->prepare_gc = GC_PREPARING;
+}
+
static bool gc_should_run(struct cache_set *c)
{
struct cache *ca;
@@ -1814,8 +1854,33 @@ static bool gc_should_run(struct cache_set *c)
if (ca->invalidate_needs_gc)
return true;
- if (atomic_read(&c->sectors_to_gc) < 0)
- return true;
+ if (atomic_read(&c->sectors_to_gc) < 0) {
+ mutex_lock(&c->bucket_lock);
+ if (cache_gc_prepare_none(c)) {
+ /*
+ * notify allocator thread to prepare for GC
+ */
+ set_cache_gc_preparing(c);
+ mutex_unlock(&c->bucket_lock);
+ pr_info("gc preparing");
+ return false;
+ } else if (cache_gc_prepare_ok(c)) {
+ /*
+ * alloc thread finished preparing,
+ * and continue to GC
+ */
+ set_cache_gc_prepare_none(c);
+ mutex_unlock(&c->bucket_lock);
+ pr_info("gc prepared ok");
+ return true;
+ } else {
+ /*
+ * waitting allocator finishing prepareing
+ */
+ mutex_unlock(&c->bucket_lock);
+ return false;
+ }
+ }
return false;
}
diff --git a/drivers/md/bcache/btree.h b/drivers/md/bcache/btree.h
index d211e2c..e60bd7a 100644
--- a/drivers/md/bcache/btree.h
+++ b/drivers/md/bcache/btree.h
@@ -102,6 +102,10 @@
#include "bset.h"
#include "debug.h"
+#define GC_PREPARE_NONE 0
+#define GC_PREPARING 1
+#define GC_PREPARED 2
+
struct btree_write {
atomic_t *journal;
--
1.8.3.1
