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The first locking issue was due to the semaphore I used. I was trying
to be overly clever and the context switch when the semaphore was busy was destroying performance. Converting to a simple spin lock bough me a factor of 50 or so. That said it's still not good enough. Tests show bad performance and we are still CPU bound. The logical fix is I need to implement per-cpu hot caches to minimize the SMP contention. Linux and Solaris both have this, I was hoping to do without but it looks like that's not to be. kmem_lock: time (sec) slabs objs hash kmem_lock: tot/max/calc tot/max/calc size/depth kmem_lock: 0.022000000 7/6/64 224/177/2048 32768/1 kmem_lock: 0.039000000 13/13/128 416/404/4096 32768/1 kmem_lock: 0.079000000 23/21/256 736/672/8192 32768/1 kmem_lock: 0.158000000 48/47/512 1536/1504/16384 32768/1 kmem_lock: 0.345000000 105/105/1024 3360/3358/32768 32768/2 kmem_lock: 0.760000000 202/200/2048 6464/6400/65536 32768/3 git-svn-id: https://outreach.scidac.gov/svn/spl/trunk@135 7e1ea52c-4ff2-0310-8f11-9dd32ca42a1c
This commit is contained in:
behlendo
parent
44b8f1769f
commit
d46630e0f3
@ -364,7 +364,7 @@ extern int kmem_set_warning(int flag);
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#define SKS_MAGIC 0x22222222
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#define SKC_MAGIC 0x2c2c2c2c
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#define SPL_KMEM_CACHE_HASH_BITS 12 /* 4k, sized for 1000's of objs */
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#define SPL_KMEM_CACHE_HASH_BITS 12
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#define SPL_KMEM_CACHE_HASH_ELTS (1 << SPL_KMEM_CACHE_HASH_BITS)
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#define SPL_KMEM_CACHE_HASH_SIZE (sizeof(struct hlist_head) * \
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SPL_KMEM_CACHE_HASH_ELTS)
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@ -417,16 +417,16 @@ typedef struct spl_kmem_cache {
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struct list_head skc_list; /* List of caches linkage */
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struct list_head skc_complete_list;/* Completely alloc'ed */
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struct list_head skc_partial_list; /* Partially alloc'ed */
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struct rw_semaphore skc_sem; /* Cache semaphore */
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spinlock_t skc_lock; /* Cache lock */
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uint64_t skc_slab_fail; /* Slab alloc failures */
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uint64_t skc_slab_create;/* Slab creates */
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uint64_t skc_slab_destroy;/* Slab destroys */
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uint64_t skc_slab_total; /* Slab total */
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uint64_t skc_slab_alloc; /* Slab alloc */
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uint64_t skc_slab_max; /* Slab max */
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uint64_t skc_obj_total; /* Obj total */
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uint64_t skc_obj_alloc; /* Obj alloc */
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uint64_t skc_obj_max; /* Obj max */
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uint64_t skc_slab_total; /* Slab total current */
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uint64_t skc_slab_alloc; /* Slab alloc current */
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uint64_t skc_slab_max; /* Slab max historic */
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uint64_t skc_obj_total; /* Obj total current */
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uint64_t skc_obj_alloc; /* Obj alloc current */
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uint64_t skc_obj_max; /* Obj max historic */
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uint64_t skc_hash_depth; /* Hash depth */
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uint64_t skc_hash_max; /* Hash depth max */
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} spl_kmem_cache_t;
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@ -221,7 +221,7 @@ out:
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}
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/* Removes slab from complete or partial list, so it must
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* be called with the 'skc->skc_sem' semaphore held.
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* be called with the 'skc->skc_lock' held.
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* */
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static void
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slab_free(spl_kmem_slab_t *sks) {
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@ -236,9 +236,9 @@ slab_free(spl_kmem_slab_t *sks) {
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skc->skc_obj_total -= sks->sks_objs;
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skc->skc_slab_total--;
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#ifdef CONFIG_RWSEM_GENERIC_SPINLOCK
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ASSERT(rwsem_is_locked(&skc->skc_sem));
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#endif
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//#ifdef CONFIG_RWSEM_GENERIC_SPINLOCK
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ASSERT(spin_is_locked(&skc->skc_lock));
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//#endif
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list_for_each_entry_safe(sko, n, &sks->sks_free_list, sko_list) {
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ASSERT(sko->sko_magic == SKO_MAGIC);
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@ -267,9 +267,9 @@ __slab_reclaim(spl_kmem_cache_t *skc)
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int rc = 0;
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ENTRY;
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#ifdef CONFIG_RWSEM_GENERIC_SPINLOCK
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ASSERT(rwsem_is_locked(&skc->skc_sem));
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#endif
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//#ifdef CONFIG_RWSEM_GENERIC_SPINLOCK
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ASSERT(spin_is_locked(&skc->skc_lock));
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//#endif
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/*
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* Free empty slabs which have not been touched in skc_delay
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* seconds. This delay time is important to avoid thrashing.
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@ -296,9 +296,9 @@ slab_reclaim(spl_kmem_cache_t *skc)
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int rc;
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ENTRY;
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down_write(&skc->skc_sem);
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spin_lock(&skc->skc_lock);
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rc = __slab_reclaim(skc);
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up_write(&skc->skc_sem);
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spin_unlock(&skc->skc_lock);
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RETURN(rc);
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}
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@ -363,7 +363,7 @@ spl_kmem_cache_create(char *name, size_t size, size_t align,
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INIT_LIST_HEAD(&skc->skc_list);
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INIT_LIST_HEAD(&skc->skc_complete_list);
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INIT_LIST_HEAD(&skc->skc_partial_list);
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init_rwsem(&skc->skc_sem);
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spin_lock_init(&skc->skc_lock);
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skc->skc_slab_fail = 0;
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skc->skc_slab_create = 0;
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skc->skc_slab_destroy = 0;
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@ -398,7 +398,7 @@ spl_kmem_cache_destroy(spl_kmem_cache_t *skc)
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list_del_init(&skc->skc_list);
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up_write(&spl_kmem_cache_sem);
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down_write(&skc->skc_sem);
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spin_lock(&skc->skc_lock);
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/* Validate there are no objects in use and free all the
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* spl_kmem_slab_t, spl_kmem_obj_t, and object buffers.
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@ -411,7 +411,7 @@ spl_kmem_cache_destroy(spl_kmem_cache_t *skc)
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kmem_free(skc->skc_hash, skc->skc_hash_size);
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kmem_free(skc->skc_name, skc->skc_name_size);
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kmem_free(skc, sizeof(*skc));
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up_write(&skc->skc_sem);
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spin_unlock(&skc->skc_lock);
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EXIT;
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}
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@ -441,7 +441,7 @@ spl_kmem_cache_alloc(spl_kmem_cache_t *skc, int flags)
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unsigned long key;
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ENTRY;
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down_write(&skc->skc_sem);
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spin_lock(&skc->skc_lock);
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restart:
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/* Check for available objects from the partial slabs */
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if (!list_empty(&skc->skc_partial_list)) {
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@ -459,7 +459,7 @@ restart:
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/* Remove from sks_free_list, add to used hash */
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list_del_init(&sko->sko_list);
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key = spl_hash_ptr(sko->sko_addr, skc->skc_hash_bits);
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hlist_add_head_rcu(&sko->sko_hlist, &skc->skc_hash[key]);
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hlist_add_head(&sko->sko_hlist, &skc->skc_hash[key]);
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sks->sks_age = jiffies;
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atomic_inc(&sks->sks_ref);
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@ -484,7 +484,7 @@ restart:
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GOTO(out_lock, obj = sko->sko_addr);
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}
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up_write(&skc->skc_sem);
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spin_unlock(&skc->skc_lock);
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/* No available objects create a new slab. Since this is an
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* expensive operation we do it without holding the semaphore
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@ -521,14 +521,14 @@ restart:
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/* Link the newly created slab in to the skc_partial_list,
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* and retry the allocation which will now succeed.
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*/
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down_write(&skc->skc_sem);
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spin_lock(&skc->skc_lock);
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skc->skc_slab_total++;
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skc->skc_obj_total += sks->sks_objs;
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list_add_tail(&sks->sks_list, &skc->skc_partial_list);
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GOTO(restart, obj = NULL);
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out_lock:
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up_write(&skc->skc_sem);
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spin_unlock(&skc->skc_lock);
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out:
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RETURN(obj);
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}
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@ -537,16 +537,20 @@ EXPORT_SYMBOL(spl_kmem_cache_alloc);
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void
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spl_kmem_cache_free(spl_kmem_cache_t *skc, void *obj)
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{
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struct hlist_head *head;
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struct hlist_node *node;
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spl_kmem_slab_t *sks = NULL;
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spl_kmem_obj_t *sko = NULL;
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unsigned long key = spl_hash_ptr(obj, skc->skc_hash_bits);
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int i = 0;
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ENTRY;
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down_write(&skc->skc_sem);
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spin_lock(&skc->skc_lock);
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hlist_for_each_entry(sko, node, &skc->skc_hash[key], sko_hlist) {
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if (unlikely((++i) > skc->skc_hash_depth))
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skc->skc_hash_depth = i;
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head = &skc->skc_hash[spl_hash_ptr(obj, skc->skc_hash_bits)];
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hlist_for_each_entry_rcu(sko, node, head, sko_hlist) {
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if (sko->sko_addr == obj) {
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ASSERT(sko->sko_magic == SKO_MAGIC);
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sks = sko->sko_slab;
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@ -583,7 +587,7 @@ spl_kmem_cache_free(spl_kmem_cache_t *skc, void *obj)
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}
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__slab_reclaim(skc);
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up_write(&skc->skc_sem);
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spin_unlock(&skc->skc_lock);
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}
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EXPORT_SYMBOL(spl_kmem_cache_free);
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@ -584,11 +584,11 @@ splat_kmem_test8(struct file *file, void *arg)
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kcp.kcp_file = file;
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splat_vprint(file, SPLAT_KMEM_TEST8_NAME, "%s",
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"time (sec)\tslabs \tobjs\n");
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"time (sec)\tslabs \tobjs \thash\n");
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splat_vprint(file, SPLAT_KMEM_TEST8_NAME, "%s",
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" \ttot/max/calc\ttot/max/calc\n");
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" \ttot/max/calc\ttot/max/calc\tsize/depth\n");
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for (alloc = 64; alloc <= 1024; alloc *= 2) {
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for (alloc = 64; alloc <= 4096; alloc *= 2) {
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kcp.kcp_size = 256;
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kcp.kcp_count = 0;
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kcp.kcp_threads = 0;
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@ -625,14 +625,16 @@ splat_kmem_test8(struct file *file, void *arg)
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delta = timespec_sub(stop, start);
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splat_vprint(file, SPLAT_KMEM_TEST8_NAME, "%2ld.%09ld\t"
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"%lu/%lu/%lu\t%lu/%lu/%lu\n",
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"%lu/%lu/%lu\t%lu/%lu/%lu\t%lu/%lu\n",
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delta.tv_sec, delta.tv_nsec,
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(unsigned long)kcp.kcp_cache->skc_slab_total,
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(unsigned long)kcp.kcp_cache->skc_slab_max,
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(unsigned long)(kcp.kcp_alloc * 32 / SPL_KMEM_CACHE_OBJ_PER_SLAB),
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(unsigned long)kcp.kcp_cache->skc_obj_total,
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(unsigned long)kcp.kcp_cache->skc_obj_max,
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(unsigned long)(kcp.kcp_alloc * 32));
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(unsigned long)(kcp.kcp_alloc * 32),
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(unsigned long)kcp.kcp_cache->skc_hash_size,
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(unsigned long)kcp.kcp_cache->skc_hash_depth);
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kmem_cache_destroy(kcp.kcp_cache);
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