From: Tang Junhui <[email protected]>
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.
The main idea of this patch is:
GC thread |
allocator thread
==>triggered by sectors_to_gc |
set ca->prepare_gc to GC_PREPARING |
to notify allocator thread to |
prepare for GC |==>detect
ca->prepare_gc is
| GC_PREPARING,
| do invalidate_buckets(),
==>waiting for allocator | and fill
free_inc queue with
thread to prepare over | reclaimable
buckets, after
| that, set ca->prepare_gc to
| GC_PREPARED to notify GC
| thread being prepared
==>detect ca->prepare_gc is |
prepared, set |
ca->prepare_gc back to |
GC_PREPARE_NONE, and continue GC |
Patch v2: Refactoring code
Signed-off-by: Tang Junhui <[email protected]>
---
drivers/md/bcache/alloc.c | 11 ++++++++-
drivers/md/bcache/bcache.h | 2 ++
drivers/md/bcache/btree.c | 59 +++++++++++++++++++++++++++++++++++++++++++---
drivers/md/bcache/btree.h | 4 ++++
4 files changed, 72 insertions(+), 4 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 5d52be8..e6d5391 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 2ad0731e..0478821 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -1805,19 +1805,72 @@ static void bch_btree_gc(struct cache_set *c)
bch_moving_gc(c);
}
+unsigned int get_cache_gc_prepare_status(struct cache_set *c)
+{
+ struct cache *ca;
+ unsigned int i;
+ unsigned int status = GC_PREPARE_NONE;
+
+ for_each_cache(ca, c, i) {
+ if (ca->prepare_gc == GC_PREPARING)
+ return GC_PREPARING;
+
+ status = ca->prepare_gc;
+ }
+
+ return status;
+}
+
+static void set_cache_gc_prepare_status(struct cache_set *c,
+ unsigned int status)
+{
+ struct cache *ca;
+ unsigned int i;
+
+ for_each_cache(ca, c, i)
+ ca->prepare_gc = status;
+}
+
static bool gc_should_run(struct cache_set *c)
{
struct cache *ca;
unsigned i;
+ bool ret = false;
for_each_cache(ca, c, i)
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) {
+ unsigned int status;
- return false;
+ mutex_lock(&c->bucket_lock);
+ status = get_cache_gc_prepare_status(c);
+ switch (status) {
+ case GC_PREPARE_NONE:
+ /*
+ * notify allocator thread to prepare for GC
+ */
+ set_cache_gc_prepare_status(c, GC_PREPARING);
+ break;
+ case GC_PREPARED:
+ /*
+ * alloc thread finished preparing,
+ * and continue to GC
+ */
+ set_cache_gc_prepare_status(c, GC_PREPARE_NONE);
+ ret = true;
+ break;
+ default:
+ /*
+ * waitting allocator finishing prepareing
+ */
+ break;
+ }
+ mutex_unlock(&c->bucket_lock);
+ }
+
+ return ret;
}
static int bch_gc_thread(void *arg)
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
