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authorChengguang Xu <cgxu519@icloud.com>2018-02-24 13:36:02 +0300
committerIlya Dryomov <idryomov@gmail.com>2018-04-02 11:12:47 +0300
commit79cd674aed7363a043222af3c8f97d0ea0a078cf (patch)
tree86fe0a19a23723b1b8ef0b0d81ebe18b04c8d4d1 /fs/ceph/caps.c
parentb517c1d87faafba0c33a38ffdd551e8b399f0a31 (diff)
downloadlinux-79cd674aed7363a043222af3c8f97d0ea0a078cf.tar.xz
ceph: optimizing cap reservation
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@icloud.com> Reviewed-by: "Yan, Zheng" <zyan@redhat.com> Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Diffstat (limited to 'fs/ceph/caps.c')
-rw-r--r--fs/ceph/caps.c88
1 files changed, 59 insertions, 29 deletions
diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index b9b5c47efd06..25141b6683e9 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -184,36 +184,54 @@ int ceph_reserve_caps(struct ceph_mds_client *mdsc,
mdsc->caps_avail_count);
spin_unlock(&mdsc->caps_list_lock);
- for (i = have; i < need; i++) {
-retry:
+ for (i = have; i < need; ) {
cap = kmem_cache_alloc(ceph_cap_cachep, GFP_NOFS);
- if (!cap) {
- if (!trimmed) {
- for (j = 0; j < mdsc->max_sessions; j++) {
- s = __ceph_lookup_mds_session(mdsc, j);
- if (!s)
- continue;
- mutex_unlock(&mdsc->mutex);
+ if (cap) {
+ list_add(&cap->caps_item, &newcaps);
+ alloc++;
+ i++;
+ continue;
+ }
- mutex_lock(&s->s_mutex);
- max_caps = s->s_nr_caps - (need - i);
- ceph_trim_caps(mdsc, s, max_caps);
- mutex_unlock(&s->s_mutex);
+ if (!trimmed) {
+ for (j = 0; j < mdsc->max_sessions; j++) {
+ s = __ceph_lookup_mds_session(mdsc, j);
+ if (!s)
+ continue;
+ mutex_unlock(&mdsc->mutex);
- ceph_put_mds_session(s);
- mutex_lock(&mdsc->mutex);
- }
- trimmed = true;
- goto retry;
- } else {
- pr_warn("reserve caps ctx=%p ENOMEM "
- "need=%d got=%d\n",
- ctx, need, have + alloc);
- goto out_nomem;
+ mutex_lock(&s->s_mutex);
+ max_caps = s->s_nr_caps - (need - i);
+ ceph_trim_caps(mdsc, s, max_caps);
+ mutex_unlock(&s->s_mutex);
+
+ ceph_put_mds_session(s);
+ mutex_lock(&mdsc->mutex);
}
+ trimmed = true;
+
+ spin_lock(&mdsc->caps_list_lock);
+ if (mdsc->caps_avail_count) {
+ int more_have;
+ if (mdsc->caps_avail_count >= need - i)
+ more_have = need - i;
+ else
+ more_have = mdsc->caps_avail_count;
+
+ i += more_have;
+ have += more_have;
+ mdsc->caps_avail_count -= more_have;
+ mdsc->caps_reserve_count += more_have;
+
+ }
+ spin_unlock(&mdsc->caps_list_lock);
+
+ continue;
}
- list_add(&cap->caps_item, &newcaps);
- alloc++;
+
+ pr_warn("reserve caps ctx=%p ENOMEM need=%d got=%d\n",
+ ctx, need, have + alloc);
+ goto out_nomem;
}
BUG_ON(have + alloc != need);
@@ -234,16 +252,28 @@ retry:
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);