When caps_avail_count is in a low level, most newly
trimmed caps will probably go into ->caps_list and
caps_avail_count will be increased. Hence after trimming,
should recheck caps_avail_count to effectly reuse
newly trimmed caps. Also, when releasing unnecessary
caps follow the same rule of ceph_put_cap.
Signed-off-by: Chengguang Xu <cgxu519@xxxxxxxxxx>
---
Only compile tested.
fs/ceph/caps.c | 41 +++++++++++++++++++++++++++++++++++++----
1 file changed, 37 insertions(+), 4 deletions(-)
diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 6582c45..ba58422 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -165,6 +165,7 @@ int ceph_reserve_caps(struct ceph_mds_client *mdsc,
int have;
int alloc = 0;
int max_caps;
+ int more_avail_caps;
bool trimmed = false;
struct ceph_mds_session *s;
LIST_HEAD(newcaps);
@@ -204,6 +205,24 @@ int ceph_reserve_caps(struct ceph_mds_client *mdsc,
mutex_lock(&mdsc->mutex);
}
trimmed = true;
+
+ spin_lock(&mdsc->caps_list_lock);
+ if (mdsc->caps_avail_count) {
+ if (mdsc->caps_avail_count + have + alloc >= need)
+ more_avail_caps = need - alloc - have;
+ else
+ more_avail_caps = mdsc->caps_avail_count;
+
+ i += more_avail_caps;
+ have += more_avail_caps;
+ mdsc->caps_avail_count -= more_avail_caps;
+ mdsc->caps_reserve_count += more_avail_caps;
+ }
+ spin_unlock(&mdsc->caps_list_lock);
+
+ if (i >= need)
+ break;
+
goto retry;
} else {
pr_warn("reserve caps ctx=%p ENOMEM "
@@ -234,16 +253,30 @@ int ceph_reserve_caps(struct ceph_mds_client *mdsc,
return 0;
out_nomem:
+
+ spin_lock(&mdsc->caps_list_lock);
+ mdsc->caps_avail_count += have;
+ mdsc->caps_reserve_count -= have;
+
while (!list_empty(&newcaps)) {
cap = list_first_entry(&newcaps,
struct ceph_cap, caps_item);
list_del(&cap->caps_item);
- kmem_cache_free(ceph_cap_cachep, cap);
+
+ /*
+ * Keep some preallocated caps around (ceph_min_count), to
+ * avoid lots of free/alloc churn.
+ */
+ if (mdsc->caps_avail_count >= mdsc->caps_reserve_count +
+ mdsc->caps_min_count) {
+ kmem_cache_free(ceph_cap_cachep, cap);
+ } else {
+ mdsc->caps_avail_count++;
+ mdsc->caps_total_count++;
+ list_add(&cap->caps_item, &mdsc->caps_list);
+ }
}
- spin_lock(&mdsc->caps_list_lock);
- mdsc->caps_avail_count += have;
- mdsc->caps_reserve_count -= have;
BUG_ON(mdsc->caps_total_count != mdsc->caps_use_count +
mdsc->caps_reserve_count +
mdsc->caps_avail_count);
--
1.8.3.1
--
To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
