| Message ID | 4c2bf8d68ffa06b212c9a4a4a095787fbdf05eb7.1640029579.git.asml.silence@gmail.com (mailing list archive) |
|---|---|
| State | RFC |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | io_uring zerocopy tx | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Guessing tree name failed - patch did not apply, async |
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index f820288092ab..5ec9e540a660 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -1095,9 +1095,12 @@ static int __ip_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;
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. 148 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/ipv4/ip_output.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)