diff mbox series

[net-next,2/2] tcp: adjust rcv zerocopy hints based on frag sizes

Message ID 20180926205704.42754-2-soheil.kdev@gmail.com
State Accepted, archived
Delegated to: David Miller
Headers show
Series [net-next,1/2] tcp: set recv_skip_hint when tcp_inq is less than PAGE_SIZE | expand

Commit Message

Soheil Hassas Yeganeh Sept. 26, 2018, 8:57 p.m. UTC 
From: Soheil Hassas Yeganeh <soheil@google.com>

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>
---
 net/ipv4/tcp.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

Comments

David Miller Oct. 2, 2018, 5:37 a.m. UTC | #1 
From: Soheil Hassas Yeganeh <soheil.kdev@gmail.com>
Date: Wed, 26 Sep 2018 16:57:04 -0400

> From: Soheil Hassas Yeganeh <soheil@google.com>
> 
> 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>

Applied.
diff mbox series

Patch

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 3e17501fc1a1..cdbd423bdeb4 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -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)