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Commit 565f0fa9 authored by Mathias Krause's avatar Mathias Krause Committed by Steffen Klassert
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xfrm: use a dedicated slab cache for struct xfrm_state 



struct xfrm_state is rather large (768 bytes here) and therefore wastes
quite a lot of memory as it falls into the kmalloc-1024 slab cache,
leaving 256 bytes of unused memory per XFRM state object -- a net waste
of 25%.

Using a dedicated slab cache for struct xfrm_state reduces the level of
internal fragmentation to a minimum.

On my configuration SLUB chooses to create a slab cache covering 4
pages holding 21 objects, resulting in an average memory waste of ~13
bytes per object -- a net waste of only 1.6%.

In my tests this led to memory savings of roughly 2.3MB for 10k XFRM
states.

Signed-off-by: default avatarMathias Krause <minipli@googlemail.com>
Signed-off-by: default avatarSteffen Klassert <steffen.klassert@secunet.com>
parent 154a8c46

net/xfrm/xfrm_state.c

+7 −2
Original line number Diff line number Diff line
@@ -42,6 +42,7 @@ static void xfrm_state_gc_task(struct work_struct *work); 


static unsigned int xfrm_state_hashmax __read_mostly = 1 * 1024 * 1024;

static __read_mostly seqcount_t xfrm_state_hash_generation = SEQCNT_ZERO(xfrm_state_hash_generation);

static struct kmem_cache *xfrm_state_cache __ro_after_init;



static DECLARE_WORK(xfrm_state_gc_work, xfrm_state_gc_task);

static HLIST_HEAD(xfrm_state_gc_list);
@@ -451,7 +452,7 @@ static void xfrm_state_gc_destroy(struct xfrm_state *x) 
	}

	xfrm_dev_state_free(x);

	security_xfrm_state_free(x);

	kfree(x);

	kmem_cache_free(xfrm_state_cache, x);

}



static void xfrm_state_gc_task(struct work_struct *work)
@@ -563,7 +564,7 @@ struct xfrm_state *xfrm_state_alloc(struct net *net) 
{

	struct xfrm_state *x;



	x = kzalloc(sizeof(struct xfrm_state), GFP_ATOMIC);

	x = kmem_cache_alloc(xfrm_state_cache, GFP_ATOMIC | __GFP_ZERO);



	if (x) {

		write_pnet(&x->xs_net, net);
@@ -2307,6 +2308,10 @@ int __net_init xfrm_state_init(struct net *net) 
{

	unsigned int sz;



	if (net_eq(net, &init_net))

		xfrm_state_cache = KMEM_CACHE(xfrm_state,

					      SLAB_HWCACHE_ALIGN | SLAB_PANIC);



	INIT_LIST_HEAD(&net->xfrm.state_all);



	sz = sizeof(struct hlist_head) * 8;