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AJvYcCXjYF6ZW58y3EZGXIu8EDE0ta5OmihEcLTioARtkNrlVKWq0iTOE395PXkyFSHydblAL3ruYyFLMg==@kvack.org X-Gm-Message-State: AOJu0YzaP2PpinLcM/+q4h2rDzXgplvkBWM1AjWDXvD2VTGkWiKsjR8w tk8vPkYs+y5b55CtDNhJiUCuVzK/ycAgyPeI8gHOnPIjMnlI/59ybLfB2y7vKbI/FLLrmHrY4Bn sHIBfjXYddpFUJDCdQx7VphD2QfitiJIYQgCOXGFH X-Gm-Gg: ASbGnctZNIxRH9edkmsm0tL8iZh038Z8AHRBmuKXR5NtmYHnozlqd19yRVZ7UFKO3iZ tQkKm1W93pWyKuLiG93vBGK7PFictTvB+F6BNzf71FZhrf/tO5/dZlAUDccfgOJ+vhUMkKc3Sqv QLht/NpsOO+nd9vS4kr0JpcvT5G5Zz+lbMhECEVzn/d83nCPmMBoqmFNZotOU7m3b/2GSZpEoH2 L4o94UCdh2FXpdKkLkZTgo= X-Google-Smtp-Source: AGHT+IE/MMrEwXrtrXpwd5NWme0SVt/1/Gn7UnQ6FdtdsnFs+oYuqBhKlvBrPCe7OGp+3lJ32hG+d0a+NMSTxCfPkqY= X-Received: by 2002:a05:622a:144d:b0:4ae:d2cc:ad51 with SMTP id d75a77b69052e-4b286cd30bemr2192291cf.1.1755577175219; Mon, 18 Aug 2025 21:19:35 -0700 (PDT) MIME-Version: 1.0 References: <20250723-slub-percpu-caches-v5-0-b792cd830f5d@suse.cz> <20250723-slub-percpu-caches-v5-1-b792cd830f5d@suse.cz> In-Reply-To: <20250723-slub-percpu-caches-v5-1-b792cd830f5d@suse.cz> From: Suren Baghdasaryan Date: Mon, 18 Aug 2025 21:19:23 -0700 X-Gm-Features: Ac12FXyNJ4RTO2e8MwHd1kDL0-WUOKScquwSWOz5-2kn6gNdbPPfPE4d6mftxNA Message-ID: Subject: Re: [PATCH v5 01/14] slab: add opt-in caching layer of percpu sheaves To: Vlastimil Babka Cc: "Liam R. Howlett" , Christoph Lameter , David Rientjes , Roman Gushchin , Harry Yoo , Uladzislau Rezki , linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcu@vger.kernel.org, maple-tree@lists.infradead.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: F0F8940007 X-Stat-Signature: yyacf6dd1x9dsyp1ehrfgd5jk5kuajec X-Rspam-User: X-HE-Tag: 1755577176-782508 X-HE-Meta: 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 n7cV6s0L 0KCNjK1+AmOVqdEHkh7cGGgfYoCbKXtT77VqejcdxF7Lej0e9k/F1+XmjSVpfsBx/Fz1LJj4z1XBFzIeQolfIBSiwb1IFbVYJY/icb4gve+GMCs7yAjsjzf44fmsV3nqGi+b2b89LxwMIKoaiWdShEJ8HMdPh0XBUMwYf9mzPZELZZtVM5Txy7TBYNNZdf2Wh7HMl X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jul 23, 2025 at 6:35=E2=80=AFAM Vlastimil Babka wr= ote: > > Specifying a non-zero value for a new struct kmem_cache_args field > sheaf_capacity will setup a caching layer of percpu arrays called > sheaves of given capacity for the created cache. > > Allocations from the cache will allocate via the percpu sheaves (main or > spare) as long as they have no NUMA node preference. Frees will also > put the object back into one of the sheaves. > > When both percpu sheaves are found empty during an allocation, an empty > sheaf may be replaced with a full one from the per-node barn. If none > are available and the allocation is allowed to block, an empty sheaf is > refilled from slab(s) by an internal bulk alloc operation. When both > percpu sheaves are full during freeing, the barn can replace a full one > with an empty one, unless over a full sheaves limit. In that case a > sheaf is flushed to slab(s) by an internal bulk free operation. Flushing > sheaves and barns is also wired to the existing cpu flushing and cache > shrinking operations. > > The sheaves do not distinguish NUMA locality of the cached objects. If > an allocation is requested with kmem_cache_alloc_node() (or a mempolicy > with strict_numa mode enabled) with a specific node (not NUMA_NO_NODE), > the sheaves are bypassed. > > The bulk operations exposed to slab users also try to utilize the > sheaves as long as the necessary (full or empty) sheaves are available > on the cpu or in the barn. Once depleted, they will fallback to bulk > alloc/free to slabs directly to avoid double copying. > > The sheaf_capacity value is exported in sysfs for observability. > > Sysfs CONFIG_SLUB_STATS counters alloc_cpu_sheaf and free_cpu_sheaf > count objects allocated or freed using the sheaves (and thus not > counting towards the other alloc/free path counters). Counters > sheaf_refill and sheaf_flush count objects filled or flushed from or to > slab pages, and can be used to assess how effective the caching is. The > refill and flush operations will also count towards the usual > alloc_fastpath/slowpath, free_fastpath/slowpath and other counters for > the backing slabs. For barn operations, barn_get and barn_put count how > many full sheaves were get from or put to the barn, the _fail variants > count how many such requests could not be satisfied mainly because the > barn was either empty or full. While the barn also holds empty sheaves > to make some operations easier, these are not as critical to mandate own > counters. Finally, there are sheaf_alloc/sheaf_free counters. > > Access to the percpu sheaves is protected by local_trylock() when > potential callers include irq context, and local_lock() otherwise (such > as when we already know the gfp flags allow blocking). The trylock > failures should be rare and we can easily fallback. Each per-NUMA-node > barn has a spin_lock. > > When slub_debug is enabled for a cache with sheaf_capacity also > specified, the latter is ignored so that allocations and frees reach the > slow path where debugging hooks are processed. Similarly, we ignore it > with CONFIG_SLUB_TINY which prefers low memory usage to performance. > > Signed-off-by: Vlastimil Babka > --- > include/linux/slab.h | 31 ++ > mm/slab.h | 2 + > mm/slab_common.c | 5 +- > mm/slub.c | 1101 ++++++++++++++++++++++++++++++++++++++++++++= +++--- > 4 files changed, 1092 insertions(+), 47 deletions(-) > > diff --git a/include/linux/slab.h b/include/linux/slab.h > index d5a8ab98035cf3e3d9043e3b038e1bebeff05b52..6cfd085907afb8fc6e502ff7a= 1a1830c52ff9125 100644 > --- a/include/linux/slab.h > +++ b/include/linux/slab.h > @@ -335,6 +335,37 @@ struct kmem_cache_args { > * %NULL means no constructor. > */ > void (*ctor)(void *); > + /** > + * @sheaf_capacity: Enable sheaves of given capacity for the cach= e. > + * > + * With a non-zero value, allocations from the cache go through c= aching > + * arrays called sheaves. Each cpu has a main sheaf that's always > + * present, and a spare sheaf thay may be not present. When both = become s/they/that > + * empty, there's an attempt to replace an empty sheaf with a ful= l sheaf > + * from the per-node barn. > + * > + * When no full sheaf is available, and gfp flags allow blocking,= a > + * sheaf is allocated and filled from slab(s) using bulk allocati= on. > + * Otherwise the allocation falls back to the normal operation > + * allocating a single object from a slab. > + * > + * Analogically when freeing and both percpu sheaves are full, th= e barn > + * may replace it with an empty sheaf, unless it's over capacity.= In > + * that case a sheaf is bulk freed to slab pages. > + * > + * The sheaves do not enforce NUMA placement of objects, so alloc= ations > + * via kmem_cache_alloc_node() with a node specified other than > + * NUMA_NO_NODE will bypass them. > + * > + * Bulk allocation and free operations also try to use the cpu sh= eaves > + * and barn, but fallback to using slab pages directly. > + * > + * When slub_debug is enabled for the cache, the sheaf_capacity a= rgument > + * is ignored. > + * > + * %0 means no sheaves will be created. > + */ > + unsigned int sheaf_capacity; > }; > > struct kmem_cache *__kmem_cache_create_args(const char *name, > diff --git a/mm/slab.h b/mm/slab.h > index 05a21dc796e095e8db934564d559494cd81746ec..1980330c2fcb4a4613a7e4f7e= fc78b349993fd89 100644 > --- a/mm/slab.h > +++ b/mm/slab.h > @@ -259,6 +259,7 @@ struct kmem_cache { > #ifndef CONFIG_SLUB_TINY > struct kmem_cache_cpu __percpu *cpu_slab; > #endif > + struct slub_percpu_sheaves __percpu *cpu_sheaves; > /* Used for retrieving partial slabs, etc. */ > slab_flags_t flags; > unsigned long min_partial; > @@ -272,6 +273,7 @@ struct kmem_cache { > /* Number of per cpu partial slabs to keep around */ > unsigned int cpu_partial_slabs; > #endif > + unsigned int sheaf_capacity; > struct kmem_cache_order_objects oo; > > /* Allocation and freeing of slabs */ > diff --git a/mm/slab_common.c b/mm/slab_common.c > index bfe7c40eeee1a01c175766935c1e3c0304434a53..e2b197e47866c30acdbd1fee4= 159f262a751c5a7 100644 > --- a/mm/slab_common.c > +++ b/mm/slab_common.c > @@ -163,6 +163,9 @@ int slab_unmergeable(struct kmem_cache *s) > return 1; > #endif > > + if (s->cpu_sheaves) > + return 1; > + > /* > * We may have set a slab to be unmergeable during bootstrap. > */ > @@ -321,7 +324,7 @@ struct kmem_cache *__kmem_cache_create_args(const cha= r *name, > object_size - args->usersize < args->useroffset)) > args->usersize =3D args->useroffset =3D 0; > > - if (!args->usersize) > + if (!args->usersize && !args->sheaf_capacity) > s =3D __kmem_cache_alias(name, object_size, args->align, = flags, > args->ctor); > if (s) > diff --git a/mm/slub.c b/mm/slub.c > index 31e11ef256f90ad8a21d6b090f810f4c991a68d6..6543aaade60b0adaab232b225= 6d65c1042c62e1c 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -346,8 +346,10 @@ static inline void debugfs_slab_add(struct kmem_cach= e *s) { } > #endif > > 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 */ > FREE_FASTPATH, /* Free to cpu slab */ > FREE_SLOWPATH, /* Freeing not to cpu slab */ > FREE_FROZEN, /* Freeing to frozen slab */ > @@ -372,6 +374,14 @@ enum stat_item { > 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 */ > + SHEAF_FREE, /* Freeing of an empty sheaf */ > + BARN_GET, /* Got full sheaf from barn */ > + BARN_GET_FAIL, /* Failed to get full sheaf from barn */ > + BARN_PUT, /* Put full sheaf to barn */ > + BARN_PUT_FAIL, /* Failed to put full sheaf to barn */ > NR_SLUB_STAT_ITEMS > }; > > @@ -418,6 +428,33 @@ void stat_add(const struct kmem_cache *s, enum stat_= item si, int v) > #endif > } > > +#define MAX_FULL_SHEAVES 10 > +#define MAX_EMPTY_SHEAVES 10 > + > +struct node_barn { > + spinlock_t lock; > + struct list_head sheaves_full; > + struct list_head sheaves_empty; > + unsigned int nr_full; > + unsigned int nr_empty; > +}; > + > +struct slab_sheaf { > + union { > + struct rcu_head rcu_head; > + struct list_head barn_list; > + }; > + unsigned int size; > + void *objects[]; > +}; > + > +struct slub_percpu_sheaves { > + local_trylock_t lock; > + struct slab_sheaf *main; /* never NULL when unlocked */ > + struct slab_sheaf *spare; /* empty or full, may be NULL */ > + struct node_barn *barn; > +}; > + > /* > * The slab lists for all objects. > */ > @@ -430,6 +467,7 @@ struct kmem_cache_node { > atomic_long_t total_objects; > struct list_head full; > #endif > + struct node_barn *barn; > }; > > static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int= node) > @@ -453,12 +491,19 @@ static inline struct kmem_cache_node *get_node(stru= ct kmem_cache *s, int node) > */ > static nodemask_t slab_nodes; > > -#ifndef CONFIG_SLUB_TINY > /* > * Workqueue used for flush_cpu_slab(). > */ > static struct workqueue_struct *flushwq; > -#endif > + > +struct slub_flush_work { > + struct work_struct work; > + struct kmem_cache *s; > + bool skip; > +}; > + > +static DEFINE_MUTEX(flush_lock); > +static DEFINE_PER_CPU(struct slub_flush_work, slub_flush); > > /******************************************************************** > * Core slab cache functions > @@ -2437,6 +2482,359 @@ static void *setup_object(struct kmem_cache *s, v= oid *object) > return object; > } > > +static struct slab_sheaf *alloc_empty_sheaf(struct kmem_cache *s, gfp_t = gfp) > +{ > + struct slab_sheaf *sheaf =3D kzalloc(struct_size(sheaf, objects, > + s->sheaf_capacity), gfp); > + > + if (unlikely(!sheaf)) > + return NULL; > + > + stat(s, SHEAF_ALLOC); > + > + return sheaf; > +} > + > +static void free_empty_sheaf(struct kmem_cache *s, struct slab_sheaf *sh= eaf) > +{ > + kfree(sheaf); > + > + stat(s, SHEAF_FREE); > +} > + > +static int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, > + size_t size, void **p); > + > + > +static int refill_sheaf(struct kmem_cache *s, struct slab_sheaf *sheaf, > + gfp_t gfp) > +{ > + int to_fill =3D s->sheaf_capacity - sheaf->size; > + int filled; > + > + if (!to_fill) > + return 0; > + > + filled =3D __kmem_cache_alloc_bulk(s, gfp, to_fill, > + &sheaf->objects[sheaf->size]); > + > + sheaf->size +=3D filled; > + > + stat_add(s, SHEAF_REFILL, filled); > + > + if (filled < to_fill) > + return -ENOMEM; > + > + return 0; > +} > + > + > +static struct slab_sheaf *alloc_full_sheaf(struct kmem_cache *s, gfp_t g= fp) > +{ > + struct slab_sheaf *sheaf =3D alloc_empty_sheaf(s, gfp); > + > + if (!sheaf) > + return NULL; > + > + if (refill_sheaf(s, sheaf, gfp)) { > + free_empty_sheaf(s, sheaf); > + return NULL; > + } > + > + return sheaf; > +} > + > +/* > + * Maximum number of objects freed during a single flush of main pcs she= af. > + * Translates directly to an on-stack array size. > + */ > +#define PCS_BATCH_MAX 32U > + > +static void __kmem_cache_free_bulk(struct kmem_cache *s, size_t size, vo= id **p); > + > +/* > + * Free all objects from the main sheaf. In order to perform > + * __kmem_cache_free_bulk() outside of cpu_sheaves->lock, work in batche= s where > + * object pointers are moved to a on-stack array under the lock. To boun= d the > + * stack usage, limit each batch to PCS_BATCH_MAX. > + * > + * returns true if at least partially flushed > + */ > +static bool sheaf_flush_main(struct kmem_cache *s) > +{ > + struct slub_percpu_sheaves *pcs; > + unsigned int batch, remaining; > + void *objects[PCS_BATCH_MAX]; > + struct slab_sheaf *sheaf; > + bool ret =3D false; > + > +next_batch: > + if (!local_trylock(&s->cpu_sheaves->lock)) > + return ret; > + > + pcs =3D this_cpu_ptr(s->cpu_sheaves); > + sheaf =3D pcs->main; > + > + batch =3D min(PCS_BATCH_MAX, sheaf->size); > + > + sheaf->size -=3D batch; > + memcpy(objects, sheaf->objects + sheaf->size, batch * sizeof(void= *)); > + > + remaining =3D sheaf->size; > + > + local_unlock(&s->cpu_sheaves->lock); > + > + __kmem_cache_free_bulk(s, batch, &objects[0]); > + > + stat_add(s, SHEAF_FLUSH, batch); > + > + ret =3D true; > + > + if (remaining) > + goto next_batch; > + > + return ret; > +} > + > +/* > + * Free all objects from a sheaf that's unused, i.e. not linked to any > + * cpu_sheaves, so we need no locking and batching. The locking is also = not > + * necessary when flushing cpu's sheaves (both spare and main) during cp= u > + * hotremove as the cpu is not executing anymore. > + */ > +static void sheaf_flush_unused(struct kmem_cache *s, struct slab_sheaf *= sheaf) > +{ > + if (!sheaf->size) > + return; > + > + stat_add(s, SHEAF_FLUSH, sheaf->size); > + > + __kmem_cache_free_bulk(s, sheaf->size, &sheaf->objects[0]); > + > + sheaf->size =3D 0; > +} > + > +/* > + * Caller needs to make sure migration is disabled in order to fully flu= sh > + * single cpu's sheaves > + * > + * must not be called from an irq > + * > + * flushing operations are rare so let's keep it simple and flush to sla= bs > + * directly, skipping the barn > + */ > +static void pcs_flush_all(struct kmem_cache *s) > +{ > + struct slub_percpu_sheaves *pcs; > + struct slab_sheaf *spare; > + > + local_lock(&s->cpu_sheaves->lock); > + pcs =3D this_cpu_ptr(s->cpu_sheaves); > + > + spare =3D pcs->spare; > + pcs->spare =3D NULL; > + > + local_unlock(&s->cpu_sheaves->lock); > + > + if (spare) { > + sheaf_flush_unused(s, spare); > + free_empty_sheaf(s, spare); > + } > + > + sheaf_flush_main(s); > +} > + > +static void __pcs_flush_all_cpu(struct kmem_cache *s, unsigned int cpu) > +{ > + struct slub_percpu_sheaves *pcs; > + > + pcs =3D per_cpu_ptr(s->cpu_sheaves, cpu); > + > + /* The cpu is not executing anymore so we don't need pcs->lock */ > + sheaf_flush_unused(s, pcs->main); > + if (pcs->spare) { > + sheaf_flush_unused(s, pcs->spare); > + free_empty_sheaf(s, pcs->spare); > + pcs->spare =3D NULL; > + } > +} > + > +static void pcs_destroy(struct kmem_cache *s) > +{ > + int cpu; > + > + for_each_possible_cpu(cpu) { > + struct slub_percpu_sheaves *pcs; > + > + pcs =3D per_cpu_ptr(s->cpu_sheaves, cpu); > + > + /* can happen when unwinding failed create */ > + if (!pcs->main) > + continue; > + > + /* > + * We have already passed __kmem_cache_shutdown() so ever= ything > + * was flushed and there should be no objects allocated f= rom > + * slabs, otherwise kmem_cache_destroy() would have abort= ed. > + * Therefore something would have to be really wrong if t= he > + * warnings here trigger, and we should rather leave obje= cts and > + * sheaves to leak in that case. > + */ > + > + WARN_ON(pcs->spare); > + > + if (!WARN_ON(pcs->main->size)) { > + free_empty_sheaf(s, pcs->main); > + pcs->main =3D NULL; > + } > + } > + > + free_percpu(s->cpu_sheaves); > + s->cpu_sheaves =3D NULL; > +} > + > +static struct slab_sheaf *barn_get_empty_sheaf(struct node_barn *barn) > +{ > + struct slab_sheaf *empty =3D NULL; > + unsigned long flags; > + > + spin_lock_irqsave(&barn->lock, flags); > + > + if (barn->nr_empty) { > + empty =3D list_first_entry(&barn->sheaves_empty, > + struct slab_sheaf, barn_list); > + list_del(&empty->barn_list); > + barn->nr_empty--; > + } > + > + spin_unlock_irqrestore(&barn->lock, flags); > + > + return empty; > +} > + > +/* > + * The following two functions are used mainly in cases where we have to= undo an > + * intended action due to a race or cpu migration. Thus they do not chec= k the > + * empty or full sheaf limits for simplicity. > + */ > + > +static void barn_put_empty_sheaf(struct node_barn *barn, struct slab_she= af *sheaf) > +{ > + unsigned long flags; > + > + spin_lock_irqsave(&barn->lock, flags); > + > + list_add(&sheaf->barn_list, &barn->sheaves_empty); > + barn->nr_empty++; > + > + spin_unlock_irqrestore(&barn->lock, flags); > +} > + > +static void barn_put_full_sheaf(struct node_barn *barn, struct slab_shea= f *sheaf) > +{ > + unsigned long flags; > + > + spin_lock_irqsave(&barn->lock, flags); > + > + list_add(&sheaf->barn_list, &barn->sheaves_full); > + barn->nr_full++; > + > + spin_unlock_irqrestore(&barn->lock, flags); > +} > + > +/* > + * If a full sheaf is available, return it and put the supplied empty on= e to > + * barn. We ignore the limit on empty sheaves as the number of sheaves d= oesn't > + * change. > + */ > +static struct slab_sheaf * > +barn_replace_empty_sheaf(struct node_barn *barn, struct slab_sheaf *empt= y) > +{ > + struct slab_sheaf *full =3D NULL; > + unsigned long flags; > + > + spin_lock_irqsave(&barn->lock, flags); > + > + if (barn->nr_full) { > + full =3D list_first_entry(&barn->sheaves_full, struct sla= b_sheaf, > + barn_list); > + list_del(&full->barn_list); > + list_add(&empty->barn_list, &barn->sheaves_empty); > + barn->nr_full--; > + barn->nr_empty++; > + } > + > + spin_unlock_irqrestore(&barn->lock, flags); > + > + return full; > +} nit: missing new line > +/* > + * If an empty sheaf is available, return it and put the supplied full o= ne to > + * barn. But if there are too many full sheaves, reject this with -E2BIG= . > + */ > +static struct slab_sheaf * > +barn_replace_full_sheaf(struct node_barn *barn, struct slab_sheaf *full) > +{ > + struct slab_sheaf *empty; > + unsigned long flags; > + > + spin_lock_irqsave(&barn->lock, flags); > + > + if (barn->nr_full >=3D MAX_FULL_SHEAVES) { > + empty =3D ERR_PTR(-E2BIG); > + } else if (!barn->nr_empty) { > + empty =3D ERR_PTR(-ENOMEM); > + } else { > + empty =3D list_first_entry(&barn->sheaves_empty, struct s= lab_sheaf, > + barn_list); > + list_del(&empty->barn_list); > + list_add(&full->barn_list, &barn->sheaves_full); > + barn->nr_empty--; > + barn->nr_full++; > + } > + > + spin_unlock_irqrestore(&barn->lock, flags); > + > + return empty; > +} > + > +static void barn_init(struct node_barn *barn) > +{ > + spin_lock_init(&barn->lock); > + INIT_LIST_HEAD(&barn->sheaves_full); > + INIT_LIST_HEAD(&barn->sheaves_empty); > + barn->nr_full =3D 0; > + barn->nr_empty =3D 0; > +} > + > +static void barn_shrink(struct kmem_cache *s, struct node_barn *barn) > +{ > + struct list_head empty_list; > + struct list_head full_list; > + struct slab_sheaf *sheaf, *sheaf2; > + unsigned long flags; > + > + INIT_LIST_HEAD(&empty_list); > + INIT_LIST_HEAD(&full_list); > + > + spin_lock_irqsave(&barn->lock, flags); > + > + list_splice_init(&barn->sheaves_full, &full_list); > + barn->nr_full =3D 0; > + list_splice_init(&barn->sheaves_empty, &empty_list); > + barn->nr_empty =3D 0; > + > + spin_unlock_irqrestore(&barn->lock, flags); > + > + list_for_each_entry_safe(sheaf, sheaf2, &full_list, barn_list) { > + sheaf_flush_unused(s, sheaf); > + free_empty_sheaf(s, sheaf); > + } > + > + list_for_each_entry_safe(sheaf, sheaf2, &empty_list, barn_list) > + free_empty_sheaf(s, sheaf); > +} > + > /* > * Slab allocation and freeing > */ > @@ -3312,11 +3710,42 @@ static inline void __flush_cpu_slab(struct kmem_c= ache *s, int cpu) > put_partials_cpu(s, c); > } > > -struct slub_flush_work { > - struct work_struct work; > - struct kmem_cache *s; > - bool skip; > -}; > +static inline void flush_this_cpu_slab(struct kmem_cache *s) > +{ > + struct kmem_cache_cpu *c =3D this_cpu_ptr(s->cpu_slab); > + > + if (c->slab) > + flush_slab(s, c); > + > + put_partials(s); > +} > + > +static bool has_cpu_slab(int cpu, struct kmem_cache *s) > +{ > + struct kmem_cache_cpu *c =3D per_cpu_ptr(s->cpu_slab, cpu); > + > + return c->slab || slub_percpu_partial(c); > +} > + > +#else /* CONFIG_SLUB_TINY */ > +static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu) { } > +static inline bool has_cpu_slab(int cpu, struct kmem_cache *s) { return = false; } > +static inline void flush_this_cpu_slab(struct kmem_cache *s) { } > +#endif /* CONFIG_SLUB_TINY */ > + > +static bool has_pcs_used(int cpu, struct kmem_cache *s) > +{ > + struct slub_percpu_sheaves *pcs; > + > + if (!s->cpu_sheaves) > + return false; > + > + pcs =3D per_cpu_ptr(s->cpu_sheaves, cpu); > + > + return (pcs->spare || pcs->main->size); > +} > + > +static void pcs_flush_all(struct kmem_cache *s); > > /* > * Flush cpu slab. > @@ -3326,30 +3755,18 @@ struct slub_flush_work { > static void flush_cpu_slab(struct work_struct *w) > { > struct kmem_cache *s; > - struct kmem_cache_cpu *c; > struct slub_flush_work *sfw; > > sfw =3D container_of(w, struct slub_flush_work, work); > > s =3D sfw->s; > - c =3D this_cpu_ptr(s->cpu_slab); > > - if (c->slab) > - flush_slab(s, c); > + if (s->cpu_sheaves) > + pcs_flush_all(s); > > - put_partials(s); > + flush_this_cpu_slab(s); > } > > -static bool has_cpu_slab(int cpu, struct kmem_cache *s) > -{ > - struct kmem_cache_cpu *c =3D per_cpu_ptr(s->cpu_slab, cpu); > - > - return c->slab || slub_percpu_partial(c); > -} > - > -static DEFINE_MUTEX(flush_lock); > -static DEFINE_PER_CPU(struct slub_flush_work, slub_flush); > - > static void flush_all_cpus_locked(struct kmem_cache *s) > { > struct slub_flush_work *sfw; > @@ -3360,7 +3777,7 @@ static void flush_all_cpus_locked(struct kmem_cache= *s) > > for_each_online_cpu(cpu) { > sfw =3D &per_cpu(slub_flush, cpu); > - if (!has_cpu_slab(cpu, s)) { > + if (!has_cpu_slab(cpu, s) && !has_pcs_used(cpu, s)) { > sfw->skip =3D true; > continue; > } > @@ -3396,19 +3813,15 @@ static int slub_cpu_dead(unsigned int cpu) > struct kmem_cache *s; > > mutex_lock(&slab_mutex); > - list_for_each_entry(s, &slab_caches, list) > + list_for_each_entry(s, &slab_caches, list) { > __flush_cpu_slab(s, cpu); > + if (s->cpu_sheaves) > + __pcs_flush_all_cpu(s, cpu); > + } > mutex_unlock(&slab_mutex); > return 0; > } > > -#else /* CONFIG_SLUB_TINY */ > -static inline void flush_all_cpus_locked(struct kmem_cache *s) { } > -static inline void flush_all(struct kmem_cache *s) { } > -static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu) { } > -static inline int slub_cpu_dead(unsigned int cpu) { return 0; } > -#endif /* CONFIG_SLUB_TINY */ > - > /* > * Check if the objects in a per cpu structure fit numa > * locality expectations. > @@ -4158,6 +4571,199 @@ bool slab_post_alloc_hook(struct kmem_cache *s, s= truct list_lru *lru, > return memcg_slab_post_alloc_hook(s, lru, flags, size, p); > } > > +static struct slub_percpu_sheaves * > +__pcs_handle_empty(struct kmem_cache *s, struct slub_percpu_sheaves *pcs= , gfp_t gfp) The naming is a bit ambiguous IMO. Maybe __pcs_replace_empty_main() ? > +{ > + struct slab_sheaf *empty =3D NULL; > + struct slab_sheaf *full; > + bool can_alloc; > + Can we add lockdep_assert_held(this_cpu_ptr(&s->cpu_sheaves->lock))? More for documentation purposes than anything else. > + if (pcs->spare && pcs->spare->size > 0) { > + swap(pcs->main, pcs->spare); > + return pcs; > + } > + > + full =3D barn_replace_empty_sheaf(pcs->barn, pcs->main); > + > + if (full) { > + stat(s, BARN_GET); > + pcs->main =3D full; > + return pcs; > + } > + > + stat(s, BARN_GET_FAIL); > + > + can_alloc =3D gfpflags_allow_blocking(gfp); > + > + if (can_alloc) { > + if (pcs->spare) { > + empty =3D pcs->spare; > + pcs->spare =3D NULL; > + } else { > + empty =3D barn_get_empty_sheaf(pcs->barn); > + } > + } > + > + local_unlock(&s->cpu_sheaves->lock); > + > + if (!can_alloc) > + return NULL; > + > + if (empty) { > + if (!refill_sheaf(s, empty, gfp)) { > + full =3D empty; > + } else { > + /* > + * we must be very low on memory so don't bother > + * with the barn > + */ > + free_empty_sheaf(s, empty); > + } > + } else { > + full =3D alloc_full_sheaf(s, gfp); > + } > + > + if (!full) > + return NULL; > + > + /* > + * we can reach here only when gfpflags_allow_blocking > + * so this must not be an irq > + */ > + local_lock(&s->cpu_sheaves->lock); > + pcs =3D this_cpu_ptr(s->cpu_sheaves); > + > + /* > + * If we are returning empty sheaf, we either got it from the > + * barn or had to allocate one. If we are returning a full > + * sheaf, it's due to racing or being migrated to a different > + * cpu. Breaching the barn's sheaf limits should be thus rare > + * enough so just ignore them to simplify the recovery. > + */ > + > + if (pcs->main->size =3D=3D 0) { > + barn_put_empty_sheaf(pcs->barn, pcs->main); > + pcs->main =3D full; > + return pcs; > + } > + > + if (!pcs->spare) { > + pcs->spare =3D full; > + return pcs; > + } > + > + if (pcs->spare->size =3D=3D 0) { > + barn_put_empty_sheaf(pcs->barn, pcs->spare); > + pcs->spare =3D full; > + return pcs; > + } > + > + barn_put_full_sheaf(pcs->barn, full); > + stat(s, BARN_PUT); > + > + return pcs; > +} > + > +static __fastpath_inline > +void *alloc_from_pcs(struct kmem_cache *s, gfp_t gfp) > +{ > + struct slub_percpu_sheaves *pcs; > + void *object; > + > +#ifdef CONFIG_NUMA > + if (static_branch_unlikely(&strict_numa)) { > + if (current->mempolicy) > + return NULL; > + } > +#endif > + > + if (!local_trylock(&s->cpu_sheaves->lock)) > + return NULL; > + > + pcs =3D this_cpu_ptr(s->cpu_sheaves); > + > + if (unlikely(pcs->main->size =3D=3D 0)) { > + pcs =3D __pcs_handle_empty(s, pcs, gfp); > + if (unlikely(!pcs)) > + return NULL; > + } > + > + object =3D pcs->main->objects[--pcs->main->size]; > + > + local_unlock(&s->cpu_sheaves->lock); > + > + stat(s, ALLOC_PCS); > + > + return object; > +} > + > +static __fastpath_inline > +unsigned int alloc_from_pcs_bulk(struct kmem_cache *s, size_t size, void= **p) > +{ > + struct slub_percpu_sheaves *pcs; > + struct slab_sheaf *main; > + unsigned int allocated =3D 0; > + unsigned int batch; > + > +next_batch: > + if (!local_trylock(&s->cpu_sheaves->lock)) > + return allocated; > + > + pcs =3D this_cpu_ptr(s->cpu_sheaves); > + > + if (unlikely(pcs->main->size =3D=3D 0)) { > + > + struct slab_sheaf *full; > + > + if (pcs->spare && pcs->spare->size > 0) { > + swap(pcs->main, pcs->spare); > + goto do_alloc; > + } > + > + full =3D barn_replace_empty_sheaf(pcs->barn, pcs->main); > + > + if (full) { > + stat(s, BARN_GET); > + pcs->main =3D full; > + goto do_alloc; > + } > + > + stat(s, BARN_GET_FAIL); > + > + local_unlock(&s->cpu_sheaves->lock); > + > + /* > + * Once full sheaves in barn are depleted, let the bulk > + * allocation continue from slab pages, otherwise we woul= d just > + * be copying arrays of pointers twice. > + */ > + return allocated; > + } > + > +do_alloc: > + > + main =3D pcs->main; > + batch =3D min(size, main->size); > + > + main->size -=3D batch; > + memcpy(p, main->objects + main->size, batch * sizeof(void *)); > + > + local_unlock(&s->cpu_sheaves->lock); > + > + stat_add(s, ALLOC_PCS, batch); > + > + allocated +=3D batch; > + > + if (batch < size) { > + p +=3D batch; > + size -=3D batch; > + goto next_batch; > + } > + > + return allocated; > +} > + > + > /* > * Inlined fastpath so that allocation functions (kmalloc, kmem_cache_al= loc) > * have the fastpath folded into their functions. So no function call > @@ -4182,7 +4788,11 @@ static __fastpath_inline void *slab_alloc_node(str= uct kmem_cache *s, struct list > if (unlikely(object)) > goto out; > > - object =3D __slab_alloc_node(s, gfpflags, node, addr, orig_size); > + if (s->cpu_sheaves && node =3D=3D NUMA_NO_NODE) > + object =3D alloc_from_pcs(s, gfpflags); > + > + if (!object) > + object =3D __slab_alloc_node(s, gfpflags, node, addr, ori= g_size); > > maybe_wipe_obj_freeptr(s, object); > init =3D slab_want_init_on_alloc(gfpflags, s); > @@ -4554,6 +5164,274 @@ static void __slab_free(struct kmem_cache *s, str= uct slab *slab, > discard_slab(s, slab); > } > > +/* > + * pcs is locked. We should have get rid of the spare sheaf and obtained= an > + * empty sheaf, while the main sheaf is full. We want to install the emp= ty sheaf > + * as a main sheaf, and make the current main sheaf a spare sheaf. > + * > + * However due to having relinquished the cpu_sheaves lock when obtainin= g > + * the empty sheaf, we need to handle some unlikely but possible cases. > + * > + * If we put any sheaf to barn here, it's because we were interrupted or= have > + * been migrated to a different cpu, which should be rare enough so just= ignore > + * the barn's limits to simplify the handling. > + * > + * An alternative scenario that gets us here is when we fail > + * barn_replace_full_sheaf(), because there's no empty sheaf available i= n the > + * barn, so we had to allocate it by alloc_empty_sheaf(). But because we= saw the > + * limit on full sheaves was not exceeded, we assume it didn't change an= d just > + * put the full sheaf there. > + */ > +static void __pcs_install_empty_sheaf(struct kmem_cache *s, > + struct slub_percpu_sheaves *pcs, struct slab_sheaf *empty= ) > +{ lockdep_assert_held(this_cpu_ptr(&s->cpu_sheaves->lock)) > + /* This is what we expect to find if nobody interrupted us. */ > + if (likely(!pcs->spare)) { > + pcs->spare =3D pcs->main; > + pcs->main =3D empty; > + return; > + } > + > + /* > + * Unlikely because if the main sheaf had space, we would have ju= st > + * freed to it. Get rid of our empty sheaf. > + */ > + if (pcs->main->size < s->sheaf_capacity) { > + barn_put_empty_sheaf(pcs->barn, empty); > + return; > + } > + > + /* Also unlikely for the same reason/ */ > + if (pcs->spare->size < s->sheaf_capacity) { > + swap(pcs->main, pcs->spare); > + barn_put_empty_sheaf(pcs->barn, empty); > + return; > + } > + > + /* > + * We probably failed barn_replace_full_sheaf() due to no empty s= heaf > + * available there, but we allocated one, so finish the job. > + */ > + barn_put_full_sheaf(pcs->barn, pcs->main); > + stat(s, BARN_PUT); > + pcs->main =3D empty; > +} > + IIUC s->cpu_sheaves->lock is locked when we enter __pcs_handle_full(), it is still locked if this function returns a valid object and it's unlocked if NULL gets returned. A comment clarifying these locking rules would be great. > +static struct slub_percpu_sheaves * > +__pcs_handle_full(struct kmem_cache *s, struct slub_percpu_sheaves *pcs) __pcs_replace_full_main() ? > +{ > + struct slab_sheaf *empty; > + bool put_fail; lockdep_assert_held(this_cpu_ptr(&s->cpu_sheaves->lock)) > + > +restart: > + put_fail =3D false; > + > + if (!pcs->spare) { > + empty =3D barn_get_empty_sheaf(pcs->barn); > + if (empty) { > + pcs->spare =3D pcs->main; > + pcs->main =3D empty; > + return pcs; > + } > + goto alloc_empty; > + } > + > + if (pcs->spare->size < s->sheaf_capacity) { > + swap(pcs->main, pcs->spare); > + return pcs; > + } > + > + empty =3D barn_replace_full_sheaf(pcs->barn, pcs->main); > + > + if (!IS_ERR(empty)) { > + stat(s, BARN_PUT); > + pcs->main =3D empty; > + return pcs; > + } > + > + if (PTR_ERR(empty) =3D=3D -E2BIG) { > + /* Since we got here, spare exists and is full */ > + struct slab_sheaf *to_flush =3D pcs->spare; > + > + stat(s, BARN_PUT_FAIL); > + > + pcs->spare =3D NULL; > + local_unlock(&s->cpu_sheaves->lock); > + > + sheaf_flush_unused(s, to_flush); > + empty =3D to_flush; > + goto got_empty; > + } > + > + /* > + * We could not replace full sheaf because barn had no empty > + * sheaves. We can still allocate it and put the full sheaf in > + * __pcs_install_empty_sheaf(), but if we fail to allocate it, > + * make sure to count the fail. > + */ > + put_fail =3D true; > + > +alloc_empty: > + local_unlock(&s->cpu_sheaves->lock); > + > + empty =3D alloc_empty_sheaf(s, GFP_NOWAIT); > + if (empty) > + goto got_empty; > + > + if (put_fail) > + stat(s, BARN_PUT_FAIL); > + > + if (!sheaf_flush_main(s)) > + return NULL; > + > + if (!local_trylock(&s->cpu_sheaves->lock)) > + return NULL; > + > + /* > + * we flushed the main sheaf so it should be empty now, > + * but in case we got preempted or migrated, we need to > + * check again > + */ > + if (pcs->main->size =3D=3D s->sheaf_capacity) > + goto restart; > + > + return pcs; > + > +got_empty: > + if (!local_trylock(&s->cpu_sheaves->lock)) { > + barn_put_empty_sheaf(pcs->barn, empty); > + return NULL; > + } > + > + pcs =3D this_cpu_ptr(s->cpu_sheaves); > + __pcs_install_empty_sheaf(s, pcs, empty); > + > + return pcs; > +} > + > +/* > + * Free an object to the percpu sheaves. > + * The object is expected to have passed slab_free_hook() already. > + */ > +static __fastpath_inline > +bool free_to_pcs(struct kmem_cache *s, void *object) > +{ > + struct slub_percpu_sheaves *pcs; > + > + if (!local_trylock(&s->cpu_sheaves->lock)) > + return false; > + > + pcs =3D this_cpu_ptr(s->cpu_sheaves); > + > + if (unlikely(pcs->main->size =3D=3D s->sheaf_capacity)) { > + > + pcs =3D __pcs_handle_full(s, pcs); > + if (unlikely(!pcs)) > + return false; > + } > + > + pcs->main->objects[pcs->main->size++] =3D object; > + > + local_unlock(&s->cpu_sheaves->lock); > + > + stat(s, FREE_PCS); > + > + return true; > +} > + > +/* > + * Bulk free objects to the percpu sheaves. > + * Unlike free_to_pcs() this includes the calls to all necessary hooks > + * and the fallback to freeing to slab pages. > + */ > +static void free_to_pcs_bulk(struct kmem_cache *s, size_t size, void **p= ) > +{ > + struct slub_percpu_sheaves *pcs; > + struct slab_sheaf *main, *empty; > + unsigned int batch, i =3D 0; > + bool init; > + > + init =3D slab_want_init_on_free(s); > + > + while (i < size) { > + struct slab *slab =3D virt_to_slab(p[i]); > + > + memcg_slab_free_hook(s, slab, p + i, 1); > + alloc_tagging_slab_free_hook(s, slab, p + i, 1); > + > + if (unlikely(!slab_free_hook(s, p[i], init, false))) { > + p[i] =3D p[--size]; > + if (!size) > + return; > + continue; > + } > + > + i++; > + } > + > +next_batch: > + if (!local_trylock(&s->cpu_sheaves->lock)) > + goto fallback; > + > + pcs =3D this_cpu_ptr(s->cpu_sheaves); > + > + if (likely(pcs->main->size < s->sheaf_capacity)) > + goto do_free; > + > + if (!pcs->spare) { > + empty =3D barn_get_empty_sheaf(pcs->barn); > + if (!empty) > + goto no_empty; > + > + pcs->spare =3D pcs->main; > + pcs->main =3D empty; > + goto do_free; > + } > + > + if (pcs->spare->size < s->sheaf_capacity) { > + swap(pcs->main, pcs->spare); > + goto do_free; > + } > + > + empty =3D barn_replace_full_sheaf(pcs->barn, pcs->main); > + if (IS_ERR(empty)) { > + stat(s, BARN_PUT_FAIL); > + goto no_empty; > + } > + > + stat(s, BARN_PUT); > + pcs->main =3D empty; > + > +do_free: > + main =3D pcs->main; > + batch =3D min(size, s->sheaf_capacity - main->size); > + > + memcpy(main->objects + main->size, p, batch * sizeof(void *)); > + main->size +=3D batch; > + > + local_unlock(&s->cpu_sheaves->lock); > + > + stat_add(s, FREE_PCS, batch); > + > + if (batch < size) { > + p +=3D batch; > + size -=3D batch; > + goto next_batch; > + } > + > + return; > + > +no_empty: > + local_unlock(&s->cpu_sheaves->lock); > + > + /* > + * if we depleted all empty sheaves in the barn or there are too > + * many full sheaves, free the rest to slab pages > + */ > +fallback: > + __kmem_cache_free_bulk(s, size, p); > +} > + > #ifndef CONFIG_SLUB_TINY > /* > * Fastpath with forced inlining to produce a kfree and kmem_cache_free = that > @@ -4640,7 +5518,10 @@ void slab_free(struct kmem_cache *s, struct slab *= slab, void *object, > memcg_slab_free_hook(s, slab, &object, 1); > alloc_tagging_slab_free_hook(s, slab, &object, 1); > > - if (likely(slab_free_hook(s, object, slab_want_init_on_free(s), f= alse))) > + if (unlikely(!slab_free_hook(s, object, slab_want_init_on_free(s)= , false))) > + return; > + > + if (!s->cpu_sheaves || !free_to_pcs(s, object)) > do_slab_free(s, slab, object, object, 1, addr); > } > > @@ -5236,6 +6117,15 @@ void kmem_cache_free_bulk(struct kmem_cache *s, si= ze_t size, void **p) > if (!size) > return; > > + /* > + * freeing to sheaves is so incompatible with the detached freeli= st so > + * once we go that way, we have to do everything differently > + */ > + if (s && s->cpu_sheaves) { > + free_to_pcs_bulk(s, size, p); > + return; > + } > + > do { > struct detached_freelist df; > > @@ -5354,7 +6244,7 @@ static int __kmem_cache_alloc_bulk(struct kmem_cach= e *s, gfp_t flags, > int kmem_cache_alloc_bulk_noprof(struct kmem_cache *s, gfp_t flags, size= _t size, > void **p) > { > - int i; > + unsigned int i =3D 0; > > if (!size) > return 0; > @@ -5363,9 +6253,20 @@ int kmem_cache_alloc_bulk_noprof(struct kmem_cache= *s, gfp_t flags, size_t size, > if (unlikely(!s)) > return 0; > > - i =3D __kmem_cache_alloc_bulk(s, flags, size, p); > - if (unlikely(i =3D=3D 0)) > - return 0; > + if (s->cpu_sheaves) > + i =3D alloc_from_pcs_bulk(s, size, p); > + > + if (i < size) { > + /* > + * If we ran out of memory, don't bother with freeing bac= k to > + * the percpu sheaves, we have bigger problems. > + */ > + if (unlikely(__kmem_cache_alloc_bulk(s, flags, size - i, = p + i) =3D=3D 0)) { > + if (i > 0) > + __kmem_cache_free_bulk(s, i, p); > + return 0; > + } > + } > > /* > * memcg and kmem_cache debug support and memory initialization. > @@ -5375,11 +6276,11 @@ int kmem_cache_alloc_bulk_noprof(struct kmem_cach= e *s, gfp_t flags, size_t size, > slab_want_init_on_alloc(flags, s), s->object_size))) = { > return 0; > } > - return i; > + > + return size; > } > EXPORT_SYMBOL(kmem_cache_alloc_bulk_noprof); > > - > /* > * Object placement in a slab is made very easy because we always start = at > * offset 0. If we tune the size of the object to the alignment then we = can > @@ -5513,7 +6414,7 @@ static inline int calculate_order(unsigned int size= ) > } > > static void > -init_kmem_cache_node(struct kmem_cache_node *n) > +init_kmem_cache_node(struct kmem_cache_node *n, struct node_barn *barn) > { > n->nr_partial =3D 0; > spin_lock_init(&n->list_lock); > @@ -5523,6 +6424,9 @@ init_kmem_cache_node(struct kmem_cache_node *n) > atomic_long_set(&n->total_objects, 0); > INIT_LIST_HEAD(&n->full); > #endif > + n->barn =3D barn; > + if (barn) > + barn_init(barn); > } > > #ifndef CONFIG_SLUB_TINY > @@ -5553,6 +6457,30 @@ static inline int alloc_kmem_cache_cpus(struct kme= m_cache *s) > } > #endif /* CONFIG_SLUB_TINY */ > > +static int init_percpu_sheaves(struct kmem_cache *s) > +{ > + int cpu; > + > + for_each_possible_cpu(cpu) { > + struct slub_percpu_sheaves *pcs; > + int nid; > + > + pcs =3D per_cpu_ptr(s->cpu_sheaves, cpu); > + > + local_trylock_init(&pcs->lock); > + > + nid =3D cpu_to_mem(cpu); > + > + pcs->barn =3D get_node(s, nid)->barn; > + pcs->main =3D alloc_empty_sheaf(s, GFP_KERNEL); > + > + if (!pcs->main) > + return -ENOMEM; > + } > + > + return 0; > +} > + > static struct kmem_cache *kmem_cache_node; > > /* > @@ -5588,7 +6516,7 @@ static void early_kmem_cache_node_alloc(int node) > slab->freelist =3D get_freepointer(kmem_cache_node, n); > slab->inuse =3D 1; > kmem_cache_node->node[node] =3D n; > - init_kmem_cache_node(n); > + init_kmem_cache_node(n, NULL); > inc_slabs_node(kmem_cache_node, node, slab->objects); > > /* > @@ -5604,6 +6532,13 @@ static void free_kmem_cache_nodes(struct kmem_cach= e *s) > struct kmem_cache_node *n; > > for_each_kmem_cache_node(s, node, n) { > + if (n->barn) { > + WARN_ON(n->barn->nr_full); > + WARN_ON(n->barn->nr_empty); > + kfree(n->barn); > + n->barn =3D NULL; > + } > + > s->node[node] =3D NULL; > kmem_cache_free(kmem_cache_node, n); > } > @@ -5612,6 +6547,8 @@ static void free_kmem_cache_nodes(struct kmem_cache= *s) > void __kmem_cache_release(struct kmem_cache *s) > { > cache_random_seq_destroy(s); > + if (s->cpu_sheaves) > + pcs_destroy(s); > #ifndef CONFIG_SLUB_TINY > free_percpu(s->cpu_slab); > #endif > @@ -5624,20 +6561,29 @@ static int init_kmem_cache_nodes(struct kmem_cach= e *s) > > for_each_node_mask(node, slab_nodes) { > struct kmem_cache_node *n; > + struct node_barn *barn =3D NULL; > > if (slab_state =3D=3D DOWN) { > early_kmem_cache_node_alloc(node); > continue; > } > + > + if (s->cpu_sheaves) { > + barn =3D kmalloc_node(sizeof(*barn), GFP_KERNEL, = node); > + > + if (!barn) > + return 0; > + } > + > n =3D kmem_cache_alloc_node(kmem_cache_node, > GFP_KERNEL, node); > - > if (!n) { > - free_kmem_cache_nodes(s); Why do you skip free_kmem_cache_nodes() here? > + kfree(barn); > return 0; > } > > - init_kmem_cache_node(n); > + init_kmem_cache_node(n, barn); > + > s->node[node] =3D n; > } > return 1; > @@ -5894,6 +6840,8 @@ int __kmem_cache_shutdown(struct kmem_cache *s) > flush_all_cpus_locked(s); > /* Attempt to free all objects */ > for_each_kmem_cache_node(s, node, n) { > + if (n->barn) > + barn_shrink(s, n->barn); > free_partial(s, n); > if (n->nr_partial || node_nr_slabs(n)) > return 1; > @@ -6097,6 +7045,9 @@ static int __kmem_cache_do_shrink(struct kmem_cache= *s) > for (i =3D 0; i < SHRINK_PROMOTE_MAX; i++) > INIT_LIST_HEAD(promote + i); > > + if (n->barn) > + barn_shrink(s, n->barn); > + > spin_lock_irqsave(&n->list_lock, flags); > > /* > @@ -6209,12 +7160,24 @@ static int slab_mem_going_online_callback(void *a= rg) > */ > mutex_lock(&slab_mutex); > list_for_each_entry(s, &slab_caches, list) { > + struct node_barn *barn =3D NULL; > + > /* > * The structure may already exist if the node was previo= usly > * onlined and offlined. > */ > if (get_node(s, nid)) > continue; > + > + if (s->cpu_sheaves) { > + barn =3D kmalloc_node(sizeof(*barn), GFP_KERNEL, = nid); > + > + if (!barn) { > + ret =3D -ENOMEM; > + goto out; > + } > + } > + > /* > * XXX: kmem_cache_alloc_node will fallback to other node= s > * since memory is not yet available from the node t= hat > @@ -6222,10 +7185,13 @@ static int slab_mem_going_online_callback(void *a= rg) > */ > n =3D kmem_cache_alloc(kmem_cache_node, GFP_KERNEL); > if (!n) { > + kfree(barn); > ret =3D -ENOMEM; > goto out; > } > - init_kmem_cache_node(n); > + > + init_kmem_cache_node(n, barn); > + > s->node[nid] =3D n; > } > /* > @@ -6444,6 +7410,17 @@ int do_kmem_cache_create(struct kmem_cache *s, con= st char *name, > > set_cpu_partial(s); > > + if (args->sheaf_capacity && !IS_ENABLED(CONFIG_SLUB_TINY) > + && !(s->flags & SLAB_DEBUG_FLAGS)= ) { > + s->cpu_sheaves =3D alloc_percpu(struct slub_percpu_sheave= s); > + if (!s->cpu_sheaves) { > + err =3D -ENOMEM; > + goto out; > + } > + // TODO: increase capacity to grow slab_sheaf up to next = kmalloc size? > + s->sheaf_capacity =3D args->sheaf_capacity; > + } > + > #ifdef CONFIG_NUMA > s->remote_node_defrag_ratio =3D 1000; > #endif > @@ -6460,6 +7437,12 @@ int do_kmem_cache_create(struct kmem_cache *s, con= st char *name, > if (!alloc_kmem_cache_cpus(s)) > goto out; > > + if (s->cpu_sheaves) { > + err =3D init_percpu_sheaves(s); > + if (err) > + goto out; > + } > + > err =3D 0; > > /* Mutex is not taken during early boot */ > @@ -6481,7 +7464,6 @@ int do_kmem_cache_create(struct kmem_cache *s, cons= t char *name, > __kmem_cache_release(s); > return err; > } > - > #ifdef SLAB_SUPPORTS_SYSFS > static int count_inuse(struct slab *slab) > { > @@ -6912,6 +7894,12 @@ static ssize_t order_show(struct kmem_cache *s, ch= ar *buf) > } > SLAB_ATTR_RO(order); > > +static ssize_t sheaf_capacity_show(struct kmem_cache *s, char *buf) > +{ > + return sysfs_emit(buf, "%u\n", s->sheaf_capacity); > +} > +SLAB_ATTR_RO(sheaf_capacity); > + > static ssize_t min_partial_show(struct kmem_cache *s, char *buf) > { > return sysfs_emit(buf, "%lu\n", s->min_partial); > @@ -7259,8 +8247,10 @@ 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_FASTPATH, free_fastpath); > STAT_ATTR(FREE_SLOWPATH, free_slowpath); > STAT_ATTR(FREE_FROZEN, free_frozen); > @@ -7285,6 +8275,14 @@ 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); > +STAT_ATTR(SHEAF_FREE, sheaf_free); > +STAT_ATTR(BARN_GET, barn_get); > +STAT_ATTR(BARN_GET_FAIL, barn_get_fail); > +STAT_ATTR(BARN_PUT, barn_put); > +STAT_ATTR(BARN_PUT_FAIL, barn_put_fail); > #endif /* CONFIG_SLUB_STATS */ > > #ifdef CONFIG_KFENCE > @@ -7315,6 +8313,7 @@ static struct attribute *slab_attrs[] =3D { > &object_size_attr.attr, > &objs_per_slab_attr.attr, > &order_attr.attr, > + &sheaf_capacity_attr.attr, > &min_partial_attr.attr, > &cpu_partial_attr.attr, > &objects_partial_attr.attr, > @@ -7346,8 +8345,10 @@ static struct attribute *slab_attrs[] =3D { > &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_fastpath_attr.attr, > &free_slowpath_attr.attr, > &free_frozen_attr.attr, > @@ -7372,6 +8373,14 @@ static struct attribute *slab_attrs[] =3D { > &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, > + &sheaf_free_attr.attr, > + &barn_get_attr.attr, > + &barn_get_fail_attr.attr, > + &barn_put_attr.attr, > + &barn_put_fail_attr.attr, > #endif > #ifdef CONFIG_FAILSLAB > &failslab_attr.attr, > > -- > 2.50.1 >