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| author | Paolo Abeni <pabeni@redhat.com> | 2022-02-04 12:28:37 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2022-02-05 15:13:52 +0000 |
| commit | de5a1f3ce4c862150dc442530dba19e1d1dc6bc2 (patch) | |
| tree | e17d79dcb5e9da6ab7fa80a4e506c1437415648b /net | |
| parent | 7881453e4adf497cf9109c84fa21eedda9ac6164 (diff) | |
| download | linux-stable-de5a1f3ce4c862150dc442530dba19e1d1dc6bc2.tar.gz linux-stable-de5a1f3ce4c862150dc442530dba19e1d1dc6bc2.tar.bz2 linux-stable-de5a1f3ce4c862150dc442530dba19e1d1dc6bc2.zip | |
net: gro: minor optimization for dev_gro_receive()
While inspecting some perf report, I noticed that the compiler
emits suboptimal code for the napi CB initialization, fetching
and storing multiple times the memory for flags bitfield.
This is with gcc 10.3.1, but I observed the same with older compiler
versions.
We can help the compiler to do a nicer work clearing several
fields at once using an u32 alias. The generated code is quite
smaller, with the same number of conditional.
Before:
objdump -t net/core/gro.o | grep " F .text"
0000000000000bb0 l F .text 0000000000000357 dev_gro_receive
After:
0000000000000bb0 l F .text 000000000000033c dev_gro_receive
v1 -> v2:
- use struct_group (Alexander and Alex)
RFC -> v1:
- use __struct_group to delimit the zeroed area (Alexander)
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/core/gro.c | 15 |
1 files changed, 4 insertions, 11 deletions
diff --git a/net/core/gro.c b/net/core/gro.c index d43d42215bdb..ee5e7e889d8b 100644 --- a/net/core/gro.c +++ b/net/core/gro.c @@ -459,29 +459,22 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff skb_set_network_header(skb, skb_gro_offset(skb)); skb_reset_mac_len(skb); - NAPI_GRO_CB(skb)->same_flow = 0; + BUILD_BUG_ON(sizeof_field(struct napi_gro_cb, zeroed) != sizeof(u32)); + BUILD_BUG_ON(!IS_ALIGNED(offsetof(struct napi_gro_cb, zeroed), + sizeof(u32))); /* Avoid slow unaligned acc */ + *(u32 *)&NAPI_GRO_CB(skb)->zeroed = 0; NAPI_GRO_CB(skb)->flush = skb_is_gso(skb) || skb_has_frag_list(skb); - NAPI_GRO_CB(skb)->free = 0; - NAPI_GRO_CB(skb)->encap_mark = 0; - NAPI_GRO_CB(skb)->recursion_counter = 0; - NAPI_GRO_CB(skb)->is_fou = 0; NAPI_GRO_CB(skb)->is_atomic = 1; - NAPI_GRO_CB(skb)->gro_remcsum_start = 0; /* Setup for GRO checksum validation */ switch (skb->ip_summed) { case CHECKSUM_COMPLETE: NAPI_GRO_CB(skb)->csum = skb->csum; NAPI_GRO_CB(skb)->csum_valid = 1; - NAPI_GRO_CB(skb)->csum_cnt = 0; break; case CHECKSUM_UNNECESSARY: NAPI_GRO_CB(skb)->csum_cnt = skb->csum_level + 1; - NAPI_GRO_CB(skb)->csum_valid = 0; break; - default: - NAPI_GRO_CB(skb)->csum_cnt = 0; - NAPI_GRO_CB(skb)->csum_valid = 0; } pp = INDIRECT_CALL_INET(ptype->callbacks.gro_receive, |