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authorEric Dumazet <eric.dumazet@gmail.com>2010-05-05 01:07:37 -0700
committerDavid S. Miller <davem@davemloft.net>2010-05-05 01:07:37 -0700
commitec7d2f2cf3a1b76202986519ec4f8ec75b2de232 (patch)
tree177c324eb0cf7e687d1bbd10a6add3a7d5979002 /net/core
parent8753d29fd5daf890004a38c80835e1eb3acda394 (diff)
net: __alloc_skb() speedup
With following patch I can reach maximum rate of my pktgen+udpsink simulator : - 'old' machine : dual quad core E5450 @3.00GHz - 64 UDP rx flows (only differ by destination port) - RPS enabled, NIC interrupts serviced on cpu0 - rps dispatched on 7 other cores. (~130.000 IPI per second) - SLAB allocator (faster than SLUB in this workload) - tg3 NIC - 1.080.000 pps without a single drop at NIC level. Idea is to add two prefetchw() calls in __alloc_skb(), one to prefetch first sk_buff cache line, the second to prefetch the shinfo part. Also using one memset() to initialize all skb_shared_info fields instead of one by one to reduce number of instructions, using long word moves. All skb_shared_info fields before 'dataref' are cleared in __alloc_skb(). Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/skbuff.c21
1 files changed, 5 insertions, 16 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 8b9c109166a7..a9b0e1f77806 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -181,12 +181,14 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
skb = kmem_cache_alloc_node(cache, gfp_mask & ~__GFP_DMA, node);
if (!skb)
goto out;
+ prefetchw(skb);
size = SKB_DATA_ALIGN(size);
data = kmalloc_node_track_caller(size + sizeof(struct skb_shared_info),
gfp_mask, node);
if (!data)
goto nodata;
+ prefetchw(data + size);
/*
* Only clear those fields we need to clear, not those that we will
@@ -208,15 +210,8 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
/* make sure we initialize shinfo sequentially */
shinfo = skb_shinfo(skb);
+ memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
atomic_set(&shinfo->dataref, 1);
- shinfo->nr_frags = 0;
- shinfo->gso_size = 0;
- shinfo->gso_segs = 0;
- shinfo->gso_type = 0;
- shinfo->ip6_frag_id = 0;
- shinfo->tx_flags.flags = 0;
- skb_frag_list_init(skb);
- memset(&shinfo->hwtstamps, 0, sizeof(shinfo->hwtstamps));
if (fclone) {
struct sk_buff *child = skb + 1;
@@ -505,16 +500,10 @@ int skb_recycle_check(struct sk_buff *skb, int skb_size)
return 0;
skb_release_head_state(skb);
+
shinfo = skb_shinfo(skb);
+ memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
atomic_set(&shinfo->dataref, 1);
- shinfo->nr_frags = 0;
- shinfo->gso_size = 0;
- shinfo->gso_segs = 0;
- shinfo->gso_type = 0;
- shinfo->ip6_frag_id = 0;
- shinfo->tx_flags.flags = 0;
- skb_frag_list_init(skb);
- memset(&shinfo->hwtstamps, 0, sizeof(shinfo->hwtstamps));
memset(skb, 0, offsetof(struct sk_buff, tail));
skb->data = skb->head + NET_SKB_PAD;