diff options
| author | Soheil Hassas Yeganeh <soheil@google.com> | 2016-04-03 06:08:08 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-04-04 22:50:29 +0300 |
| commit | 6b084928baac562ed61866f540a96120e9c9ddb7 (patch) | |
| tree | 775a973c0dc77e0c42c7fde2e128843d18bf95d9 /include/net/tcp.h | |
| parent | 6db8b963a7a31047573f229492ff6fc0f51cc377 (diff) | |
| download | linux-6b084928baac562ed61866f540a96120e9c9ddb7.tar.xz | |
tcp: use one bit in TCP_SKB_CB to mark ACK timestamps
Currently, to avoid a cache line miss for accessing skb_shinfo,
tcp_ack_tstamp skips socket that do not have
SOF_TIMESTAMPING_TX_ACK bit set in sk_tsflags. This is
implemented based on an implicit assumption that the
SOF_TIMESTAMPING_TX_ACK is set via socket options for the
duration that ACK timestamps are needed.
To implement per-write timestamps, this check should be
removed and replaced with a per-packet alternative that
quickly skips packets missing ACK timestamps marks without
a cache-line miss.
To enable per-packet marking without a cache line miss, use
one bit in TCP_SKB_CB to mark a whether a SKB might need a
ack tx timestamp or not. Further checks in tcp_ack_tstamp are not
modified and work as before.
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/tcp.h')
| -rw-r--r-- | include/net/tcp.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h index f8bb4a4ed3d1..a23282996ca9 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -754,7 +754,8 @@ struct tcp_skb_cb { TCPCB_REPAIRED) __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */ - /* 1 byte hole */ + __u8 txstamp_ack:1, /* Record TX timestamp for ack? */ + unused:7; __u32 ack_seq; /* Sequence number ACK'd */ union { struct inet_skb_parm h4; |