staging: lustre: obdclass: 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.

Signed-off-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-7896
Reviewed-on: http://review.whamcloud.com/19082
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/lustre/lustre/include/lu_object.h b/drivers/staging/lustre/lustre/include/lu_object.h
index 0826c19..7a4f412 100644 (file)
--- a/drivers/staging/lustre/lustre/include/lu_object.h
+++ b/drivers/staging/lustre/lustre/include/lu_object.h
@@ -712,8 +712,14 @@ 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_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,
+                         bool 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, true);
+}
 
 void lu_site_print(const struct lu_env *env, struct lu_site *s, void *cookie,
                   lu_printer_t printer);

diff --git a/drivers/staging/lustre/lustre/obdclass/lu_object.c b/drivers/staging/lustre/lustre/obdclass/lu_object.c
index 1805861..abcf951 100644 (file)
--- a/drivers/staging/lustre/lustre/obdclass/lu_object.c
+++ b/drivers/staging/lustre/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
@@ -329,8 +329,11 @@ 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 false, 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, bool canblock)
 {
        struct lu_object_header *h;
        struct lu_object_header *temp;
@@ -360,7 +363,11 @@ 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)
+               mutex_lock(&s->ls_purge_mutex);
+       else if (!mutex_trylock(&s->ls_purge_mutex))
+               goto out;
+
        did_sth = 0;
        cfs_hash_for_each_bucket(s->ls_obj_hash, &bd, i) {
                if (i < start)
@@ -414,10 +421,10 @@ 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.
@@ -625,9 +632,12 @@ static void lu_object_limit(const struct lu_env *env, struct lu_device *dev)
 
        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_t(__u64, size - nr, LU_CACHE_NR_MAX_ADJUST));
+       if (size <= nr)
+               return;
+
+       lu_site_purge_objects(env, dev->ld_site,
+                             min_t(__u64, size - nr, LU_CACHE_NR_MAX_ADJUST),
+                             false);
 }
 
 static struct lu_object *lu_object_new(const struct lu_env *env,