Messages in this thread Patch in this message | | | From | Pavel Begunkov <> | Subject | [RFC v2 09/19] ipv6: avoid partial copy for zc | Date | Tue, 21 Dec 2021 15:35:31 +0000 |
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Even when zerocopy transmission is requested and possible, __ip_append_data() will still copy a small chunk of data just because it allocated some extra linear space (e.g. 128 bytes). It wastes CPU cycles on copy and iter manipulations and also misalignes potentially aligned data. Avoid such coies. And as a bonus we can allocate smaller skb.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> --- net/ipv6/ip6_output.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 822e3894dd3b..3ca07d2ea9ca 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -1626,9 +1626,12 @@ static int __ip6_append_data(struct sock *sk, (fraglen + alloc_extra < SKB_MAX_ALLOC || !(rt->dst.dev->features & NETIF_F_SG))) alloclen = fraglen; - else { + else if (!zc) { alloclen = min_t(int, fraglen, MAX_HEADER); pagedlen = fraglen - alloclen; + } else { + alloclen = fragheaderlen + transhdrlen; + pagedlen = datalen - transhdrlen; } alloclen += alloc_extra; -- 2.34.1
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