LU-7896: do not call lu_site_purge() for single object exceed

first of all, this is expensive procedure including a global
mutex and per-bucket spinlocks. also, all the threads observed
exceed will be calling lu_site_purge() and essentially serialized
on that. instead we can let other threads to skip the whole
procedure.

Change-Id: Ib5d213c70b5a2f259153ab24d7c3f5a3e97239df
Signed-off-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-on: http://review.whamcloud.com/19082
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>

diff --git a/lustre/include/lu_object.h b/lustre/include/lu_object.h
index 18f1ad6..e8e4cf4 100644 (file)
--- a/lustre/include/lu_object.h
+++ b/lustre/include/lu_object.h
@@ -729,8 +729,14 @@ static inline int lu_object_is_dying(const struct lu_object_header *h)
 void lu_object_put(const struct lu_env *env, struct lu_object *o);
 void lu_object_put_nocache(const struct lu_env *env, struct lu_object *o);
 void lu_object_unhash(const struct lu_env *env, struct lu_object *o);
+int lu_site_purge_objects(const struct lu_env *env, struct lu_site *s, int nr,
+                         int canblock);
 
-int lu_site_purge(const struct lu_env *env, struct lu_site *s, int nr);
+static inline int lu_site_purge(const struct lu_env *env, struct lu_site *s,
+                               int nr)
+{
+       return lu_site_purge_objects(env, s, nr, 1);
+}
 
 void lu_site_print(const struct lu_env *env, struct lu_site *s, void *cookie,
                    lu_printer_t printer);

diff --git a/lustre/obdclass/lu_object.c b/lustre/obdclass/lu_object.c
index 5cce81b..f76917c 100644 (file)
--- a/lustre/obdclass/lu_object.c
+++ b/lustre/obdclass/lu_object.c
@@ -60,7 +60,7 @@ enum {
        LU_CACHE_PERCENT_DEFAULT = 20
 };
 
-#define        LU_CACHE_NR_MAX_ADJUST          128
+#define        LU_CACHE_NR_MAX_ADJUST          512
 #define        LU_CACHE_NR_UNLIMITED           -1
 #define        LU_CACHE_NR_DEFAULT             LU_CACHE_NR_UNLIMITED
 #define        LU_CACHE_NR_LDISKFS_LIMIT       LU_CACHE_NR_UNLIMITED
@@ -348,8 +348,11 @@ static void lu_object_free(const struct lu_env *env, struct lu_object *o)
 
 /**
  * Free \a nr objects from the cold end of the site LRU list.
+ * if canblock is 0, then don't block awaiting for another
+ * instance of lu_site_purge() to complete
  */
-int lu_site_purge(const struct lu_env *env, struct lu_site *s, int nr)
+int lu_site_purge_objects(const struct lu_env *env, struct lu_site *s,
+                         int nr, int canblock)
 {
         struct lu_object_header *h;
         struct lu_object_header *temp;
@@ -379,7 +382,11 @@ int lu_site_purge(const struct lu_env *env, struct lu_site *s, int nr)
         * It doesn't make any sense to make purge threads parallel, that can
         * only bring troubles to us. See LU-5331.
         */
-       mutex_lock(&s->ls_purge_mutex);
+       if (canblock != 0)
+               mutex_lock(&s->ls_purge_mutex);
+       else if (mutex_trylock(&s->ls_purge_mutex) == 0)
+               goto out;
+
         did_sth = 0;
         cfs_hash_for_each_bucket(s->ls_obj_hash, &bd, i) {
                 if (i < start)
@@ -435,9 +442,10 @@ int lu_site_purge(const struct lu_env *env, struct lu_site *s, int nr)
         /* race on s->ls_purge_start, but nobody cares */
         s->ls_purge_start = i % CFS_HASH_NBKT(s->ls_obj_hash);
 
+out:
         return nr;
 }
-EXPORT_SYMBOL(lu_site_purge);
+EXPORT_SYMBOL(lu_site_purge_objects);
 
 /*
  * Object printing.
@@ -665,11 +673,11 @@ static void lu_object_limit(const struct lu_env *env,
 
        size = cfs_hash_size_get(dev->ld_site->ls_obj_hash);
        nr = (__u64)lu_cache_nr;
-       if (size > nr)
-               lu_site_purge(env, dev->ld_site,
-                             MIN(size - nr, LU_CACHE_NR_MAX_ADJUST));
+       if (size <= nr)
+               return;
 
-       return;
+       lu_site_purge_objects(env, dev->ld_site,
+                             MIN(size - nr, LU_CACHE_NR_MAX_ADJUST), 0);
 }
 
 static struct lu_object *lu_object_new(const struct lu_env *env,