> 在 2018年3月5日，上午11:05，Yan, Zheng <zyan@xxxxxxxxxx> 写道：
>
>
>
>> 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.
I’ll put more attention on it next time.
Thanks,
Chengguang.
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