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net: optimize GRO for the common case.

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After the previous patches, at GRO time, skb->slow_gro is
usually 0, unless the packets comes from some H/W offload
slowpath or tunnel.

We can optimize the GRO code assuming !skb->slow_gro is likely.
This remove multiple conditionals in the most common path, at the
price of an additional one when we hit the above "slow-paths".

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Paolo Abeni 2021-07-28 18:24:02 +02:00 committed by David S. Miller
parent b0999f385a
commit 9efb4b5baf
2 changed files with 28 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
net/core/dev.c
View File

@ -6014,7 +6014,6 @@ static void gro_list_prepare(const struct list_head *head,
diffs |= skb_vlan_tag_present(p) ^ skb_vlan_tag_present(skb);
if (skb_vlan_tag_present(p))
diffs |= skb_vlan_tag_get(p) ^ skb_vlan_tag_get(skb);
diffs |= skb_metadata_dst_cmp(p, skb);
diffs |= skb_metadata_differs(p, skb);
if (maclen == ETH_HLEN)
diffs |= compare_ether_header(skb_mac_header(p),
@ -6024,17 +6023,29 @@ static void gro_list_prepare(const struct list_head *head,
skb_mac_header(skb),
maclen);
diffs |= skb_get_nfct(p) ^ skb_get_nfct(skb);
/* in most common scenarions _state is 0
* otherwise we are already on some slower paths
* either skip all the infrequent tests altogether or
* avoid trying too hard to skip each of them individually
*/
if (!diffs && unlikely(skb->slow_gro | p->slow_gro)) {
#if IS_ENABLED(CONFIG_SKB_EXTENSIONS) && IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
if (!diffs) {
struct tc_skb_ext *skb_ext = skb_ext_find(skb, TC_SKB_EXT);
struct tc_skb_ext *p_ext = skb_ext_find(p, TC_SKB_EXT);
struct tc_skb_ext *skb_ext;
struct tc_skb_ext *p_ext;
#endif
diffs |= skb_metadata_dst_cmp(p, skb);
diffs |= skb_get_nfct(p) ^ skb_get_nfct(skb);
#if IS_ENABLED(CONFIG_SKB_EXTENSIONS) && IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
skb_ext = skb_ext_find(skb, TC_SKB_EXT);
p_ext = skb_ext_find(p, TC_SKB_EXT);
diffs |= (!!p_ext) ^ (!!skb_ext);
if (!diffs && unlikely(skb_ext))
diffs |= p_ext->chain ^ skb_ext->chain;
}
#endif
}
NAPI_GRO_CB(p)->same_flow = !diffs;
}
@ -6299,8 +6310,11 @@ static void napi_reuse_skb(struct napi_struct *napi, struct sk_buff *skb)
skb->encapsulation = 0;
skb_shinfo(skb)->gso_type = 0;
skb->truesize = SKB_TRUESIZE(skb_end_offset(skb));
skb_ext_reset(skb);
nf_reset_ct(skb);
if (unlikely(skb->slow_gro)) {
skb_ext_reset(skb);
nf_reset_ct(skb);
skb->slow_gro = 0;
}
napi->skb = skb;
}

9
net/core/skbuff.c
View File

@ -954,9 +954,12 @@ void __kfree_skb_defer(struct sk_buff *skb)
void napi_skb_free_stolen_head(struct sk_buff *skb)
{
nf_reset_ct(skb);
skb_dst_drop(skb);
skb_ext_put(skb);
if (unlikely(skb->slow_gro)) {
nf_reset_ct(skb);
skb_dst_drop(skb);
skb_ext_put(skb);
skb->slow_gro = 0;
}
napi_skb_cache_put(skb);
}