> On 24 Feb 2018, at 18:36, Chengguang Xu <cgxu519@xxxxxxxxxx> wrote:
>
> 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
Some lines exceed 80 characters. I make some modification to patch.
Regards
Yan, Zheng
>
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