From c73e5807e4f6fc6d373a5db55b45f639f8bb6328 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 11 Nov 2018 07:34:28 -0800 Subject: 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 Signed-off-by: David S. Miller --- Documentation/networking/ip-sysctl.txt | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'Documentation') 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 -- cgit v1.2.3