[PATCH net-next 4/6] net: optimize GRO for the common case.
From: Paolo Abeni <pabeni@redhat.com>
Date: 2021-07-28 16:24:47
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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> --- net/core/dev.c | 30 ++++++++++++++++++++++-------- net/core/skbuff.c | 9 ++++++--- 2 files changed, 28 insertions(+), 11 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index fb5d12a3d52d..19565f7497ee 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c@@ -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) + 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) - 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); + 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; }
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index a990e11c393c..8231cbddb6ed 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c@@ -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); }
--
2.26.3