Commit 6f191218 authored by Vlastimil Babka's avatar Vlastimil Babka
Browse files

mm/slub: cleanup and repurpose some stat items 



A number of stat items related to cpu slabs became unused, remove them.

Two of those were ALLOC_FASTPATH and FREE_FASTPATH. But instead of
removing those, use them instead of ALLOC_PCS and FREE_PCS, since
sheaves are the new (and only) fastpaths, Remove the recently added
_PCS variants instead.

Change where FREE_SLOWPATH is counted so that it only counts freeing of
objects by slab users that (for whatever reason) do not go to a percpu
sheaf, and not all (including internal) callers of __slab_free(). Thus
sheaf flushing (already counted by SHEAF_FLUSH) does not affect
FREE_SLOWPATH anymore. This matches how ALLOC_SLOWPATH doesn't count
sheaf refills (counted by SHEAF_REFILL).

Reviewed-by: default avatarHao Li <hao.li@linux.dev>
Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
parent fb016a5e

mm/slub.c

+26 −57
Original line number Diff line number Diff line
@@ -335,33 +335,19 @@ enum add_mode { 
};



enum stat_item {

	ALLOC_PCS,		/* Allocation from percpu sheaf */

	ALLOC_FASTPATH,		/* Allocation from cpu slab */

	ALLOC_SLOWPATH,		/* Allocation by getting a new cpu slab */

	FREE_PCS,		/* Free to percpu sheaf */

	ALLOC_FASTPATH,		/* Allocation from percpu sheaves */

	ALLOC_SLOWPATH,		/* Allocation from partial or new slab */

	FREE_RCU_SHEAF,		/* Free to rcu_free sheaf */

	FREE_RCU_SHEAF_FAIL,	/* Failed to free to a rcu_free sheaf */

	FREE_FASTPATH,		/* Free to cpu slab */

	FREE_SLOWPATH,		/* Freeing not to cpu slab */

	FREE_FASTPATH,		/* Free to percpu sheaves */

	FREE_SLOWPATH,		/* Free to a slab */

	FREE_ADD_PARTIAL,	/* Freeing moves slab to partial list */

	FREE_REMOVE_PARTIAL,	/* Freeing removes last object */

	ALLOC_FROM_PARTIAL,	/* Cpu slab acquired from node partial list */

	ALLOC_SLAB,		/* Cpu slab acquired from page allocator */

	ALLOC_REFILL,		/* Refill cpu slab from slab freelist */

	ALLOC_NODE_MISMATCH,	/* Switching cpu slab */

	ALLOC_SLAB,		/* New slab acquired from page allocator */

	ALLOC_NODE_MISMATCH,	/* Requested node different from cpu sheaf */

	FREE_SLAB,		/* Slab freed to the page allocator */

	CPUSLAB_FLUSH,		/* Abandoning of the cpu slab */

	DEACTIVATE_FULL,	/* Cpu slab was full when deactivated */

	DEACTIVATE_EMPTY,	/* Cpu slab was empty when deactivated */

	DEACTIVATE_REMOTE_FREES,/* Slab contained remotely freed objects */

	DEACTIVATE_BYPASS,	/* Implicit deactivation */

	ORDER_FALLBACK,		/* Number of times fallback was necessary */

	CMPXCHG_DOUBLE_CPU_FAIL,/* Failures of this_cpu_cmpxchg_double */

	CMPXCHG_DOUBLE_FAIL,	/* Failures of slab freelist update */

	CPU_PARTIAL_ALLOC,	/* Used cpu partial on alloc */

	CPU_PARTIAL_FREE,	/* Refill cpu partial on free */

	CPU_PARTIAL_NODE,	/* Refill cpu partial from node partial */

	CPU_PARTIAL_DRAIN,	/* Drain cpu partial to node partial */

	SHEAF_FLUSH,		/* Objects flushed from a sheaf */

	SHEAF_REFILL,		/* Objects refilled to a sheaf */

	SHEAF_ALLOC,		/* Allocation of an empty sheaf */
@@ -4350,8 +4336,10 @@ void *alloc_from_pcs(struct kmem_cache *s, gfp_t gfp, int node) 
	 * We assume the percpu sheaves contain only local objects although it's

	 * not completely guaranteed, so we verify later.

	 */

	if (unlikely(node_requested && node != numa_mem_id()))

	if (unlikely(node_requested && node != numa_mem_id())) {

		stat(s, ALLOC_NODE_MISMATCH);

		return NULL;

	}



	if (!local_trylock(&s->cpu_sheaves->lock))

		return NULL;
@@ -4374,6 +4362,7 @@ void *alloc_from_pcs(struct kmem_cache *s, gfp_t gfp, int node) 
		 */

		if (page_to_nid(virt_to_page(object)) != node) {

			local_unlock(&s->cpu_sheaves->lock);

			stat(s, ALLOC_NODE_MISMATCH);

			return NULL;

		}

	}
@@ -4382,7 +4371,7 @@ void *alloc_from_pcs(struct kmem_cache *s, gfp_t gfp, int node) 


	local_unlock(&s->cpu_sheaves->lock);



	stat(s, ALLOC_PCS);

	stat(s, ALLOC_FASTPATH);



	return object;

}
@@ -4454,7 +4443,7 @@ unsigned int alloc_from_pcs_bulk(struct kmem_cache *s, gfp_t gfp, size_t size, 


	local_unlock(&s->cpu_sheaves->lock);



	stat_add(s, ALLOC_PCS, batch);

	stat_add(s, ALLOC_FASTPATH, batch);



	allocated += batch;
@@ -5117,8 +5106,6 @@ static void __slab_free(struct kmem_cache *s, struct slab *slab, 
	unsigned long flags;

	bool on_node_partial;



	stat(s, FREE_SLOWPATH);



	if (IS_ENABLED(CONFIG_SLUB_TINY) || kmem_cache_debug(s)) {

		free_to_partial_list(s, slab, head, tail, cnt, addr);

		return;
@@ -5422,7 +5409,7 @@ bool free_to_pcs(struct kmem_cache *s, void *object, bool allow_spin) 


	local_unlock(&s->cpu_sheaves->lock);



	stat(s, FREE_PCS);

	stat(s, FREE_FASTPATH);



	return true;

}
@@ -5690,7 +5677,7 @@ static void free_to_pcs_bulk(struct kmem_cache *s, size_t size, void **p) 


	local_unlock(&s->cpu_sheaves->lock);



	stat_add(s, FREE_PCS, batch);

	stat_add(s, FREE_FASTPATH, batch);



	if (batch < size) {

		p += batch;
@@ -5712,10 +5699,12 @@ static void free_to_pcs_bulk(struct kmem_cache *s, size_t size, void **p) 
	 */

fallback:

	__kmem_cache_free_bulk(s, size, p);

	stat_add(s, FREE_SLOWPATH, size);



flush_remote:

	if (remote_nr) {

		__kmem_cache_free_bulk(s, remote_nr, &remote_objects[0]);

		stat_add(s, FREE_SLOWPATH, remote_nr);

		if (i < size) {

			remote_nr = 0;

			goto next_remote_batch;
@@ -5769,6 +5758,7 @@ static void free_deferred_objects(struct irq_work *work) 
		set_freepointer(s, x, NULL);



		__slab_free(s, slab, x, x, 1, _THIS_IP_);

		stat(s, FREE_SLOWPATH);

	}

}
@@ -5810,6 +5800,7 @@ void slab_free(struct kmem_cache *s, struct slab *slab, void *object, 
	}



	__slab_free(s, slab, object, object, 1, addr);

	stat(s, FREE_SLOWPATH);

}



#ifdef CONFIG_MEMCG
@@ -5832,8 +5823,10 @@ void slab_free_bulk(struct kmem_cache *s, struct slab *slab, void *head, 
	 * With KASAN enabled slab_free_freelist_hook modifies the freelist

	 * to remove objects, whose reuse must be delayed.

	 */

	if (likely(slab_free_freelist_hook(s, &head, &tail, &cnt)))

	if (likely(slab_free_freelist_hook(s, &head, &tail, &cnt))) {

		__slab_free(s, slab, head, tail, cnt, addr);

		stat_add(s, FREE_SLOWPATH, cnt);

	}

}



#ifdef CONFIG_SLUB_RCU_DEBUG
@@ -5858,8 +5851,10 @@ static void slab_free_after_rcu_debug(struct rcu_head *rcu_head) 
		return;



	/* resume freeing */

	if (slab_free_hook(s, object, slab_want_init_on_free(s), true))

	if (slab_free_hook(s, object, slab_want_init_on_free(s), true)) {

		__slab_free(s, slab, object, object, 1, _THIS_IP_);

		stat(s, FREE_SLOWPATH);

	}

}

#endif /* CONFIG_SLUB_RCU_DEBUG */
@@ -5867,6 +5862,7 @@ static void slab_free_after_rcu_debug(struct rcu_head *rcu_head) 
void ___cache_free(struct kmem_cache *cache, void *x, unsigned long addr)

{

	__slab_free(cache, virt_to_slab(x), x, x, 1, addr);

	stat(cache, FREE_SLOWPATH);

}

#endif
@@ -6746,6 +6742,7 @@ int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, 
		i = refill_objects(s, p, flags, size, size);

		if (i < size)

			goto error;

		stat_add(s, ALLOC_SLOWPATH, i);

	}



	return i;
@@ -8749,33 +8746,19 @@ static ssize_t text##_store(struct kmem_cache *s, \ 
}								\

SLAB_ATTR(text);						\



STAT_ATTR(ALLOC_PCS, alloc_cpu_sheaf);

STAT_ATTR(ALLOC_FASTPATH, alloc_fastpath);

STAT_ATTR(ALLOC_SLOWPATH, alloc_slowpath);

STAT_ATTR(FREE_PCS, free_cpu_sheaf);

STAT_ATTR(FREE_RCU_SHEAF, free_rcu_sheaf);

STAT_ATTR(FREE_RCU_SHEAF_FAIL, free_rcu_sheaf_fail);

STAT_ATTR(FREE_FASTPATH, free_fastpath);

STAT_ATTR(FREE_SLOWPATH, free_slowpath);

STAT_ATTR(FREE_ADD_PARTIAL, free_add_partial);

STAT_ATTR(FREE_REMOVE_PARTIAL, free_remove_partial);

STAT_ATTR(ALLOC_FROM_PARTIAL, alloc_from_partial);

STAT_ATTR(ALLOC_SLAB, alloc_slab);

STAT_ATTR(ALLOC_REFILL, alloc_refill);

STAT_ATTR(ALLOC_NODE_MISMATCH, alloc_node_mismatch);

STAT_ATTR(FREE_SLAB, free_slab);

STAT_ATTR(CPUSLAB_FLUSH, cpuslab_flush);

STAT_ATTR(DEACTIVATE_FULL, deactivate_full);

STAT_ATTR(DEACTIVATE_EMPTY, deactivate_empty);

STAT_ATTR(DEACTIVATE_REMOTE_FREES, deactivate_remote_frees);

STAT_ATTR(DEACTIVATE_BYPASS, deactivate_bypass);

STAT_ATTR(ORDER_FALLBACK, order_fallback);

STAT_ATTR(CMPXCHG_DOUBLE_CPU_FAIL, cmpxchg_double_cpu_fail);

STAT_ATTR(CMPXCHG_DOUBLE_FAIL, cmpxchg_double_fail);

STAT_ATTR(CPU_PARTIAL_ALLOC, cpu_partial_alloc);

STAT_ATTR(CPU_PARTIAL_FREE, cpu_partial_free);

STAT_ATTR(CPU_PARTIAL_NODE, cpu_partial_node);

STAT_ATTR(CPU_PARTIAL_DRAIN, cpu_partial_drain);

STAT_ATTR(SHEAF_FLUSH, sheaf_flush);

STAT_ATTR(SHEAF_REFILL, sheaf_refill);

STAT_ATTR(SHEAF_ALLOC, sheaf_alloc);
@@ -8851,33 +8834,19 @@ static struct attribute *slab_attrs[] = { 
	&remote_node_defrag_ratio_attr.attr,

#endif

#ifdef CONFIG_SLUB_STATS

	&alloc_cpu_sheaf_attr.attr,

	&alloc_fastpath_attr.attr,

	&alloc_slowpath_attr.attr,

	&free_cpu_sheaf_attr.attr,

	&free_rcu_sheaf_attr.attr,

	&free_rcu_sheaf_fail_attr.attr,

	&free_fastpath_attr.attr,

	&free_slowpath_attr.attr,

	&free_add_partial_attr.attr,

	&free_remove_partial_attr.attr,

	&alloc_from_partial_attr.attr,

	&alloc_slab_attr.attr,

	&alloc_refill_attr.attr,

	&alloc_node_mismatch_attr.attr,

	&free_slab_attr.attr,

	&cpuslab_flush_attr.attr,

	&deactivate_full_attr.attr,

	&deactivate_empty_attr.attr,

	&deactivate_remote_frees_attr.attr,

	&deactivate_bypass_attr.attr,

	&order_fallback_attr.attr,

	&cmpxchg_double_fail_attr.attr,

	&cmpxchg_double_cpu_fail_attr.attr,

	&cpu_partial_alloc_attr.attr,

	&cpu_partial_free_attr.attr,

	&cpu_partial_node_attr.attr,

	&cpu_partial_drain_attr.attr,

	&sheaf_flush_attr.attr,

	&sheaf_refill_attr.attr,

	&sheaf_alloc_attr.attr,