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authorEric Dumazet <edumazet@google.com>2018-11-11 06:41:31 -0800
committerDavid S. Miller <davem@davemloft.net>2018-11-11 13:54:53 -0800
commita682850a114aef947da5d603f7fd2cfe7eabbd72 (patch)
tree1ba9698d64af24b2567bcd2d6cc590fb140ec386 /net/ipv4/tcp_output.c
parenttcp: refine tcp_tso_should_defer() after EDT adoption (diff)
downloadlinux-dev-a682850a114aef947da5d603f7fd2cfe7eabbd72.tar.xz
linux-dev-a682850a114aef947da5d603f7fd2cfe7eabbd72.zip
tcp: get rid of tcp_tso_should_defer() dependency on HZ/jiffies
tcp_tso_should_defer() first heuristic is to not defer if last send is "old enough". Its current implementation uses jiffies and its low granularity. TSO autodefer performance should not rely on kernel HZ :/ After EDT conversion, we have state variables in nanoseconds that can allow us to properly implement the heuristic. This patch increases TSO chunk sizes on medium rate flows, especially when receivers do not use GRO or similar aggregation. It also reduces bursts for HZ=100 or HZ=250 kernels, making TCP behavior more uniform. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_output.c')
-rw-r--r--net/ipv4/tcp_output.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 78a56cef7e39..75dcf4daca72 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1920,9 +1920,12 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,
goto send_now;
/* Avoid bursty behavior by allowing defer
- * only if the last write was recent.
+ * only if the last write was recent (1 ms).
+ * Note that tp->tcp_wstamp_ns can be in the future if we have
+ * packets waiting in a qdisc or device for EDT delivery.
*/
- if ((s32)(tcp_jiffies32 - tp->lsndtime) > 0)
+ delta = tp->tcp_clock_cache - tp->tcp_wstamp_ns - NSEC_PER_MSEC;
+ if (delta > 0)
goto send_now;
in_flight = tcp_packets_in_flight(tp);