kernel.git/Documentation/networking/ip-sysctl.txt, branch linux-3.11.y

tcp: TSO packets automatic sizing

2013-11-04T12:35:11Z

[ Upstream commits 6d36824e730f247b602c90e8715a792003e3c5a7, 02cf4ebd82ff0ac7254b88e466820a290ed8289a, and parts of 7eec4174ff29cd42f2acfae8112f51c228545d40 ] After hearing many people over past years complaining against TSO being bursty or even buggy, we are proud to present automatic sizing of TSO packets. One part of the problem is that tcp_tso_should_defer() uses an heuristic relying on upcoming ACKS instead of a timer, but more generally, having big TSO packets makes little sense for low rates, as it tends to create micro bursts on the network, and general consensus is to reduce the buffering amount. This patch introduces a per socket sk_pacing_rate, that approximates the current sending rate, and allows us to size the TSO packets so that we try to send one packet every ms. This field could be set by other transports. Patch has no impact for high speed flows, where having large TSO packets makes sense to reach line rate. For other flows, this helps better packet scheduling and ACK clocking. This patch increases performance of TCP flows in lossy environments. A new sysctl (tcp_min_tso_segs) is added, to specify the minimal size of a TSO packet (default being 2). A follow-up patch will provide a new packet scheduler (FQ), using sk_pacing_rate as an input to perform optional per flow pacing. This explains why we chose to set sk_pacing_rate to twice the current rate, allowing 'slow start' ramp up. sk_pacing_rate = 2 * cwnd * mss / srtt v2: Neal Cardwell reported a suspect deferring of last two segments on initial write of 10 MSS, I had to change tcp_tso_should_defer() to take into account tp->xmit_size_goal_segs Signed-off-by: Eric Dumazet Cc: Neal Cardwell Cc: Yuchung Cheng Cc: Van Jacobson Cc: Tom Herbert Acked-by: Yuchung Cheng Acked-by: Neal Cardwell Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

2013-07-03T21:55:13Z

Conflicts: drivers/net/ethernet/freescale/fec_main.c drivers/net/ethernet/renesas/sh_eth.c net/ipv4/gre.c The GRE conflict is between a bug fix (kfree_skb --> kfree_skb_list) and the splitting of the gre.c code into seperate files. The FEC conflict was two sets of changes adding ethtool support code in an "!CONFIG_M5272" CPP protected block. Finally the sh_eth.c conflict was between one commit add bits set in the .eesr_err_check mask whilst another commit removed the .tx_error_check member and assignments. Signed-off-by: David S. Miller

tcp: doc : fix the syncookies default value

2013-06-24T07:26:26Z

syncookies is on for default since in commit e994b7c901 (tcp: Don't make syn cookies initial setting depend on CONFIG_SYSCTL). And fix a typo of CONFIG_SYN_COOKIES. Signed-off-by: Shan Wei Signed-off-by: David S. Miller

net: add doc for ip_early_demux sysctl

2013-06-12T22:10:13Z

commit 6648bd7e0e62c0c8c03b (ipv4: Add sysctl knob to control early socket demux) introduced such sysctl, but forgot to add doc into Documentation/networking/ip-sysctl.txt. This patch adds it. Basically I grab the doc from the description of commit 41063e9dd11956f2d285 (ipv4: Early TCP socket demux.) and the above commit. Cc: Eric Dumazet Cc: Alexander Duyck Cc: David S. Miller Signed-off-by: Cong Wang Signed-off-by: David S. Miller

doc:networking: Fix default value (icmp_ignore_bogus_error_responses).

2013-06-08T06:31:54Z

This patch fixes icmp_ignore_bogus_error_responses default value to be 1 instead of FALSE. It is initialized to 1 in icmp_sk_init(). Signed-off-by: Rami Rosen Signed-off-by: David S. Miller

doc:networking: Fix typo in documentation/networking

2013-05-28T06:29:18Z

Correct spelling typo Signed-off-by: Masanari Iida Signed-off-by: David S. Miller

tcp: implement RFC5682 F-RTO

2013-03-21T15:47:51Z

This patch implements F-RTO (foward RTO recovery): When the first retransmission after timeout is acknowledged, F-RTO sends new data instead of old data. If the next ACK acknowledges some never-retransmitted data, then the timeout was spurious and the congestion state is reverted. Otherwise if the next ACK selectively acknowledges the new data, then the timeout was genuine and the loss recovery continues. This idea applies to recurring timeouts as well. While F-RTO sends different data during timeout recovery, it does not (and should not) change the congestion control. The implementaion follows the three steps of SACK enhanced algorithm (section 3) in RFC5682. Step 1 is in tcp_enter_loss(). Step 2 and 3 are in tcp_process_loss(). The basic version is not supported because SACK enhanced version also works for non-SACK connections. The new implementation is functionally in parity with the old F-RTO implementation except the one case where it increases undo events: In addition to the RFC algorithm, a spurious timeout may be detected without sending data in step 2, as long as the SACK confirms not all the original data are dropped. When this happens, the sender will undo the cwnd and perhaps enter fast recovery instead. This additional check increases the F-RTO undo events by 5x compared to the prior implementation on Google Web servers, since the sender often does not have new data to send for HTTP. Note F-RTO may detect spurious timeout before Eifel with timestamps does so. Signed-off-by: Yuchung Cheng Acked-by: Eric Dumazet Acked-by: Neal Cardwell Signed-off-by: David S. Miller

tcp: refactor F-RTO

2013-03-21T15:47:50Z

The patch series refactor the F-RTO feature (RFC4138/5682). This is to simplify the loss recovery processing. Existing F-RTO was developed during the experimental stage (RFC4138) and has many experimental features. It takes a separate code path from the traditional timeout processing by overloading CA_Disorder instead of using CA_Loss state. This complicates CA_Disorder state handling because it's also used for handling dubious ACKs and undos. While the algorithm in the RFC does not change the congestion control, the implementation intercepts congestion control in various places (e.g., frto_cwnd in tcp_ack()). The new code implements newer F-RTO RFC5682 using CA_Loss processing path. F-RTO becomes a small extension in the timeout processing and interfaces with congestion control and Eifel undo modules. It lets congestion control (module) determines how many to send independently. F-RTO only chooses what to send in order to detect spurious retranmission. If timeout is found spurious it invokes existing Eifel undo algorithms like DSACK or TCP timestamp based detection. The first patch removes all F-RTO code except the sysctl_tcp_frto is left for the new implementation. Since CA_EVENT_FRTO is removed, TCP westwood now computes ssthresh on regular timeout CA_EVENT_LOSS event. Signed-off-by: Yuchung Cheng Acked-by: Neal Cardwell Acked-by: Eric Dumazet Signed-off-by: David S. Miller

tcp: Remove TCPCT

2013-03-17T18:35:13Z

TCPCT uses option-number 253, reserved for experimental use and should not be used in production environments. Further, TCPCT does not fully implement RFC 6013. As a nice side-effect, removing TCPCT increases TCP's performance for very short flows: Doing an apache-benchmark with -c 100 -n 100000, sending HTTP-requests for files of 1KB size. before this patch: average (among 7 runs) of 20845.5 Requests/Second after: average (among 7 runs) of 21403.6 Requests/Second Signed-off-by: Christoph Paasch Signed-off-by: David S. Miller

Documentation: fix neigh/default/gc_thresh1 default value.

2013-03-15T13:12:23Z

The default value is 128, not 256 #grep gc_thresh1 net/ -rI net/decnet/dn_neigh.c: .gc_thresh1 = 128, net/ipv6/ndisc.c: .gc_thresh1 = 128, net/ipv4/arp.c: .gc_thresh1 = 128, Signed-off-by: Li RongQing Signed-off-by: David S. Miller