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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>
This commit is contained in:
Chengguang Xu 2018-02-24 18:36:02 +08:00 committed by Ilya Dryomov
parent b517c1d87f
commit 79cd674aed
1 changed files with 64 additions and 34 deletions
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98
fs/ceph/caps.c
View File

@ -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);
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;
goto retry;
} else {
pr_warn("reserve caps ctx=%p ENOMEM "
"need=%d got=%d\n",
ctx, need, have + alloc);
goto out_nomem;
}
if (cap) {
list_add(&cap->caps_item, &newcaps);
alloc++;
i++;
continue;
}
list_add(&cap->caps_item, &newcaps);
alloc++;
if (!trimmed) {
for (j = 0; j < mdsc->max_sessions; j++) {
s = __ceph_lookup_mds_session(mdsc, j);
if (!s)
continue;
mutex_unlock(&mdsc->mutex);
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;
}
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:
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);
}
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);
/* 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);
}
}
BUG_ON(mdsc->caps_total_count != mdsc->caps_use_count +
mdsc->caps_reserve_count +
mdsc->caps_avail_count);