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authorEric Dumazet <edumazet@google.com>2018-11-11 07:34:28 -0800
committerDavid S. Miller <davem@davemloft.net>2018-11-11 13:57:03 -0800
commitc73e5807e4f6fc6d373a5db55b45f639f8bb6328 (patch)
tree09c332f796e245e7ec15cc31905e61f793da451b /Documentation/networking
parent83afb36a7097bdf6776e261fa3a2bf2dc5a4a8c2 (diff)
tcp: tsq: no longer use limit_output_bytes for paced flows
FQ pacing guarantees that paced packets queued by one flow do not add head-of-line blocking for other flows. After TCP GSO conversion, increasing limit_output_bytes to 1 MB is safe, since this maps to 16 skbs at most in qdisc or device queues. (or slightly more if some drivers lower {gso_max_segs|size}) We still can queue at most 1 ms worth of traffic (this can be scaled by wifi drivers if they need to) Tested: # ethtool -c eth0 | egrep "tx-usecs:|tx-frames:" # 40 Gbit mlx4 NIC tx-usecs: 16 tx-frames: 16 # tc qdisc replace dev eth0 root fq # for f in {1..10};do netperf -P0 -H lpaa24,6 -o THROUGHPUT;done Before patch: 27711 26118 27107 27377 27712 27388 27340 27117 27278 27509 After patch: 37434 36949 36658 36998 37711 37291 37605 36659 36544 37349 Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation/networking')
-rw-r--r--Documentation/networking/ip-sysctl.txt2
1 files changed, 1 insertions, 1 deletions
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index aa9e6a331679..af2a69439b93 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -759,7 +759,7 @@ tcp_limit_output_bytes - INTEGER
flows, for typical pfifo_fast qdiscs. tcp_limit_output_bytes
limits the number of bytes on qdisc or device to reduce artificial
RTT/cwnd and reduce bufferbloat.
- Default: 262144
+ Default: 1048576 (16 * 65536)
tcp_challenge_ack_limit - INTEGER
Limits number of Challenge ACK sent per second, as recommended