Commit 789762ce authored Sep 26, 2018 by Soheil Hassas Yeganeh Committed by David S. Miller Oct 01, 2018

tcp: adjust rcv zerocopy hints based on frag sizes



When SKBs are coalesced, we can have SKBs with different
frag sizes. Some with PAGE_SIZE and some not with PAGE_SIZE.
Since recv_skip_hint is always set to the full SKB size,
it can overestimate the amount that should be read using
normal read for coalesced packets.

Change the recv_skip_hint so that it only includes the first
frags that are not of PAGE_SIZE.

Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 8f2b0293

net/ipv4/tcp.c

+10 −1

Original line number	Diff line number	Diff line
		@@ -1805,8 +1805,17 @@ static int tcp_zerocopy_receive(struct sock *sk,
		frags++;
		}
		}
		if (frags->size != PAGE_SIZE \|\| frags->page_offset)
		if (frags->size != PAGE_SIZE \|\| frags->page_offset) {
		int remaining = zc->recv_skip_hint;

		while (remaining && (frags->size != PAGE_SIZE \|\|
		frags->page_offset)) {
		remaining -= frags->size;
		frags++;
		}
		zc->recv_skip_hint -= remaining;
		break;
		}
		ret = vm_insert_page(vma, address + length,
		skb_frag_page(frags));
		if (ret)

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