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: Hao Li <hao.li@linux.dev>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

diff --git a/mm/slub.c b/mm/slub.c
index 2ec4bcfb37596009805c95e75af57919cf2bb73e..eb1f52a7999941a4c995cf6cf750ad9a3590bc57 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -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 @@ do_alloc:
 
        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 @@ do_free:
 
        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 @@ no_empty:
         */
 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,