Eric Dumazet wrote:
> Some NUMA machines have a big MAX_NUMNODES (possibly 1024), but fewer
> possible nodes. This patch dynamically sizes the 'struct kmem_cache' to
> allocate only needed space.
>
> I moved nodelists[] field at the end of struct kmem_cache, and use the
> following computation in kmem_cache_init()
>
> cache_cache.buffer_size = offsetof(struct kmem_cache, nodelists) +
> nr_node_ids * sizeof(struct kmem_list3 *);
>
>
> On my two nodes x86_64 machine, kmem_cache.obj_size is now 192 instead
> of 704
> (This is because on x86_64, MAX_NUMNODES is 64)
>
> On bigger NUMA setups, this might reduce the gfporder of "cache_cache"
That is a dramatic size difference, and I seem to have 128 slabs wow.
I'll try and find some time to test this on some of our numa kit.
>
> Signed-off-by: Eric Dumazet <[EMAIL PROTECTED]>
>
>
> ------------------------------------------------------------------------
>
> diff --git a/mm/slab.c b/mm/slab.c
> index abf46ae..b187618 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -389,7 +389,6 @@ struct kmem_cache {
> unsigned int buffer_size;
> u32 reciprocal_buffer_size;
> /* 3) touched by every alloc & free from the backend */
> - struct kmem_list3 *nodelists[MAX_NUMNODES];
>
> unsigned int flags; /* constant flags */
> unsigned int num; /* # of objs per slab */
> @@ -444,6 +443,17 @@ #if DEBUG
> int obj_offset;
> int obj_size;
> #endif
> + /*
> + * We put nodelists[] at the end of kmem_cache, because we want to size
> + * this array to nr_node_ids slots instead of MAX_NUMNODES
> + * (see kmem_cache_init())
> + * We still use [MAX_NUMNODES] and not [1] or [0] because cache_cache
> + * is statically defined, so we reserve the max number of nodes.
> + */
> + struct kmem_list3 *nodelists[MAX_NUMNODES];
> + /*
> + * Do not add fields after nodelists[]
> + */
> };
>
> #define CFLGS_OFF_SLAB (0x80000000UL)
> @@ -678,9 +688,6 @@ static struct kmem_cache cache_cache = {
> .shared = 1,
> .buffer_size = sizeof(struct kmem_cache),
> .name = "kmem_cache",
> -#if DEBUG
> - .obj_size = sizeof(struct kmem_cache),
> -#endif
Is there any reason to not initialise the .obj_size here? You are
initialising both .buffer_size and .obj_size in kmem_cache_init anyhow
so I would expect either both or neither to be initialised in your new
scheme. Doing only one seems very strange.
> };
>
> #define BAD_ALIEN_MAGIC 0x01020304ul
> @@ -1437,6 +1444,15 @@ void __init kmem_cache_init(void)
> cache_cache.array[smp_processor_id()] = &initarray_cache.cache;
> cache_cache.nodelists[node] = &initkmem_list3[CACHE_CACHE];
>
> + /*
> + * struct kmem_cache size depends on nr_node_ids, which
> + * can be less than MAX_NUMNODES.
> + */
> + cache_cache.buffer_size = offsetof(struct kmem_cache, nodelists) +
> + nr_node_ids * sizeof(struct kmem_list3 *);
> +#if DEBUG
> + cache_cache.obj_size = cache_cache.buffer_size;
> +#endif
> cache_cache.buffer_size = ALIGN(cache_cache.buffer_size,
> cache_line_size());
> cache_cache.reciprocal_buffer_size =
-apw
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
