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Message-ID: <CAJuCfpEQzHM8hwTLXj8evuWHcUWvsM+HecwkLgP3i-A30rAtHQ@mail.gmail.com>
Date: Fri, 26 Sep 2025 17:28:33 -0700
From: Suren Baghdasaryan <surenb@...gle.com>
To: Vlastimil Babka <vbabka@...e.cz>
Cc: "Liam R. Howlett" <Liam.Howlett@...cle.com>, Christoph Lameter <cl@...two.org>,
David Rientjes <rientjes@...gle.com>, Roman Gushchin <roman.gushchin@...ux.dev>,
Harry Yoo <harry.yoo@...cle.com>, Uladzislau Rezki <urezki@...il.com>,
Sidhartha Kumar <sidhartha.kumar@...cle.com>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, rcu@...r.kernel.org,
maple-tree@...ts.infradead.org
Subject: Re: [PATCH v8 20/23] tools/testing: Add support for prefilled slab sheafs
On Wed, Sep 10, 2025 at 1:01 AM Vlastimil Babka <vbabka@...e.cz> wrote:
>
> From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
>
> Add the prefilled sheaf structs to the slab header and the associated
> functions to the testing/shared/linux.c file.
>
> Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
> Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
Reviewed-by: Suren Baghdasaryan <surenb@...gle.com>
> ---
> tools/include/linux/slab.h | 28 ++++++++++++++
> tools/testing/shared/linux.c | 89 ++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 117 insertions(+)
>
> diff --git a/tools/include/linux/slab.h b/tools/include/linux/slab.h
> index c5c5cc6db5668be2cc94c29065ccfa7ca7b4bb08..94937a699402bd1f31887dfb52b6fd0a3c986f43 100644
> --- a/tools/include/linux/slab.h
> +++ b/tools/include/linux/slab.h
> @@ -123,6 +123,18 @@ struct kmem_cache_args {
> void (*ctor)(void *);
> };
>
> +struct slab_sheaf {
> + union {
> + struct list_head barn_list;
> + /* only used for prefilled sheafs */
> + unsigned int capacity;
> + };
> + struct kmem_cache *cache;
> + unsigned int size;
> + int node; /* only used for rcu_sheaf */
> + void *objects[];
> +};
> +
> static inline void *kzalloc(size_t size, gfp_t gfp)
> {
> return kmalloc(size, gfp | __GFP_ZERO);
> @@ -173,5 +185,21 @@ __kmem_cache_create(const char *name, unsigned int size, unsigned int align,
> void kmem_cache_free_bulk(struct kmem_cache *cachep, size_t size, void **list);
> int kmem_cache_alloc_bulk(struct kmem_cache *cachep, gfp_t gfp, size_t size,
> void **list);
> +struct slab_sheaf *
> +kmem_cache_prefill_sheaf(struct kmem_cache *s, gfp_t gfp, unsigned int size);
> +
> +void *
> +kmem_cache_alloc_from_sheaf(struct kmem_cache *s, gfp_t gfp,
> + struct slab_sheaf *sheaf);
> +
> +void kmem_cache_return_sheaf(struct kmem_cache *s, gfp_t gfp,
> + struct slab_sheaf *sheaf);
> +int kmem_cache_refill_sheaf(struct kmem_cache *s, gfp_t gfp,
> + struct slab_sheaf **sheafp, unsigned int size);
> +
> +static inline unsigned int kmem_cache_sheaf_size(struct slab_sheaf *sheaf)
> +{
> + return sheaf->size;
> +}
>
> #endif /* _TOOLS_SLAB_H */
> diff --git a/tools/testing/shared/linux.c b/tools/testing/shared/linux.c
> index 97b8412ccbb6d222604c7b397c53c65618d8d51b..4ceff7969b78cf8e33cd1e021c68bc9f8a02a7a1 100644
> --- a/tools/testing/shared/linux.c
> +++ b/tools/testing/shared/linux.c
> @@ -137,6 +137,12 @@ void kmem_cache_free_bulk(struct kmem_cache *cachep, size_t size, void **list)
> if (kmalloc_verbose)
> pr_debug("Bulk free %p[0-%zu]\n", list, size - 1);
>
> + if (cachep->exec_callback) {
> + if (cachep->callback)
> + cachep->callback(cachep->private);
> + cachep->exec_callback = false;
> + }
> +
> pthread_mutex_lock(&cachep->lock);
> for (int i = 0; i < size; i++)
> kmem_cache_free_locked(cachep, list[i]);
> @@ -242,6 +248,89 @@ __kmem_cache_create_args(const char *name, unsigned int size,
> return ret;
> }
>
> +struct slab_sheaf *
> +kmem_cache_prefill_sheaf(struct kmem_cache *s, gfp_t gfp, unsigned int size)
> +{
> + struct slab_sheaf *sheaf;
> + unsigned int capacity;
> +
> + if (s->exec_callback) {
> + if (s->callback)
> + s->callback(s->private);
> + s->exec_callback = false;
> + }
> +
> + capacity = max(size, s->sheaf_capacity);
> +
> + sheaf = calloc(1, sizeof(*sheaf) + sizeof(void *) * capacity);
> + if (!sheaf)
> + return NULL;
> +
> + sheaf->cache = s;
> + sheaf->capacity = capacity;
> + sheaf->size = kmem_cache_alloc_bulk(s, gfp, size, sheaf->objects);
> + if (!sheaf->size) {
> + free(sheaf);
> + return NULL;
> + }
> +
> + return sheaf;
> +}
> +
> +int kmem_cache_refill_sheaf(struct kmem_cache *s, gfp_t gfp,
> + struct slab_sheaf **sheafp, unsigned int size)
> +{
> + struct slab_sheaf *sheaf = *sheafp;
> + int refill;
> +
> + if (sheaf->size >= size)
> + return 0;
> +
> + if (size > sheaf->capacity) {
> + sheaf = kmem_cache_prefill_sheaf(s, gfp, size);
> + if (!sheaf)
> + return -ENOMEM;
> +
> + kmem_cache_return_sheaf(s, gfp, *sheafp);
> + *sheafp = sheaf;
> + return 0;
> + }
> +
> + refill = kmem_cache_alloc_bulk(s, gfp, size - sheaf->size,
> + &sheaf->objects[sheaf->size]);
> + if (!refill)
> + return -ENOMEM;
> +
> + sheaf->size += refill;
> + return 0;
> +}
> +
> +void kmem_cache_return_sheaf(struct kmem_cache *s, gfp_t gfp,
> + struct slab_sheaf *sheaf)
> +{
> + if (sheaf->size)
> + kmem_cache_free_bulk(s, sheaf->size, &sheaf->objects[0]);
> +
> + free(sheaf);
> +}
> +
> +void *
> +kmem_cache_alloc_from_sheaf(struct kmem_cache *s, gfp_t gfp,
> + struct slab_sheaf *sheaf)
> +{
> + void *obj;
> +
> + if (sheaf->size == 0) {
> + printf("Nothing left in sheaf!\n");
> + return NULL;
> + }
> +
> + obj = sheaf->objects[--sheaf->size];
> + sheaf->objects[sheaf->size] = NULL;
> +
> + return obj;
> +}
> +
> /*
> * Test the test infrastructure for kem_cache_alloc/free and bulk counterparts.
> */
>
> --
> 2.51.0
>
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