- 30 3月, 2018 1 次提交
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由 John Fastabend 提交于
Add support for the BPF_F_INGRESS flag in sk_msg redirect helper. To do this add a scatterlist ring for receiving socks to check before calling into regular recvmsg call path. Additionally, because the poll wakeup logic only checked the skb recv queue we need to add a hook in TCP stack (similar to write side) so that we have a way to wake up polling socks when a scatterlist is redirected to that sock. After this all that is needed is for the redirect helper to push the scatterlist into the psock receive queue. Signed-off-by: NJohn Fastabend <john.fastabend@gmail.com> Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
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- 20 3月, 2018 1 次提交
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由 John Fastabend 提交于
When calling do_tcp_sendpages() from in kernel and we know the data has no references from user side we can omit SKBTX_SHARED_FRAG flag. This patch adds an internal flag, NO_SKBTX_SHARED_FRAG that can be used to omit setting SKBTX_SHARED_FRAG. The flag is not exposed to userspace because the sendpage call from the splice logic masks out all bits except MSG_MORE. Signed-off-by: NJohn Fastabend <john.fastabend@gmail.com> Acked-by: NDavid S. Miller <davem@davemloft.net> Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
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- 17 3月, 2018 1 次提交
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由 Yousuk Seung 提交于
This patch adds TCP_NLA_SND_SSTHRESH stat into SCM_TIMESTAMPING_OPT_STATS that reports tcp_sock.snd_ssthresh. Signed-off-by: NYousuk Seung <ysseung@google.com> Signed-off-by: NNeal Cardwell <ncardwell@google.com> Signed-off-by: NPriyaranjan Jha <priyarjha@google.com> Signed-off-by: NSoheil Hassas Yeganeh <soheil@google.com> Signed-off-by: NYuchung Cheng <ycheng@google.com> Reviewed-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 08 3月, 2018 1 次提交
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由 Soheil Hassas Yeganeh 提交于
When the connection is aborted, there is no point in keeping the packets on the write queue until the connection is closed. Similar to a27fd7a8 ('tcp: purge write queue upon RST'), this is essential for a correct MSG_ZEROCOPY implementation, because userspace cannot call close(fd) before receiving zerocopy signals even when the connection is aborted. Fixes: f214f915 ("tcp: enable MSG_ZEROCOPY") Signed-off-by: NSoheil Hassas Yeganeh <soheil@google.com> Signed-off-by: NNeal Cardwell <ncardwell@google.com> Reviewed-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NYuchung Cheng <ycheng@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 05 3月, 2018 2 次提交
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由 Priyaranjan Jha 提交于
This patch adds TCP_NLA_CA_STATE stat into SCM_TIMESTAMPING_OPT_STATS. It reports ca_state of socket, when timestamp is generated. Signed-off-by: NPriyaranjan Jha <priyarjha@google.com> Signed-off-by: NNeal Cardwell <ncardwell@google.com> Signed-off-by: NYuchung Cheng <ycheng@google.com> Signed-off-by: NSoheil Hassas Yeganeh <soheil@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Priyaranjan Jha 提交于
This patch adds TCP_NLA_SENDQ_SIZE stat into SCM_TIMESTAMPING_OPT_STATS. It reports no. of bytes present in send queue, when timestamp is generated. Signed-off-by: NPriyaranjan Jha <priyarjha@google.com> Signed-off-by: NNeal Cardwell <ncardwell@google.com> Signed-off-by: NYuchung Cheng <ycheng@google.com> Signed-off-by: NSoheil Hassas Yeganeh <soheil@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 22 2月, 2018 4 次提交
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由 Eric Dumazet 提交于
We no longer have skbs with skb->ip_summed == CHECKSUM_NONE in TCP write queues. We can remove dead code in tcp_sendmsg(). Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Eric Dumazet 提交于
Since TCP relies on GSO, we do not need this helper anymore. Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Eric Dumazet 提交于
After previous commit, sk_can_gso() is always true. Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Eric Dumazet 提交于
Oleksandr Natalenko reported performance issues with BBR without FQ packet scheduler that were root caused to lack of SG and GSO/TSO on his configuration. In this mode, TCP internal pacing has to setup a high resolution timer for each MSS sent. We could implement in TCP a strategy similar to the one adopted in commit fefa569a ("net_sched: sch_fq: account for schedule/timers drifts") or decide to finally switch TCP stack to a GSO only mode. This has many benefits : 1) Most TCP developments are done with TSO in mind. 2) Less high-resolution timers needs to be armed for TCP-pacing 3) GSO can benefit of xmit_more hint 4) Receiver GRO is more effective (as if TSO was used for real on sender) -> Lower ACK traffic 5) Write queues have less overhead (one skb holds about 64KB of payload) 6) SACK coalescing just works. 7) rtx rb-tree contains less packets, SACK is cheaper. This patch implements the minimum patch, but we can remove some legacy code as follow ups. Tested: On 40Gbit link, one netperf -t TCP_STREAM BBR+fq: sg on: 26 Gbits/sec sg off: 15.7 Gbits/sec (was 2.3 Gbit before patch) BBR+pfifo_fast: sg on: 24.2 Gbits/sec sg off: 14.9 Gbits/sec (was 0.66 Gbit before patch !!! ) BBR+fq_codel: sg on: 24.4 Gbits/sec sg off: 15 Gbits/sec (was 0.66 Gbit before patch !!! ) Signed-off-by: NEric Dumazet <edumazet@google.com> Reported-by: NOleksandr Natalenko <oleksandr@natalenko.name> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 12 2月, 2018 1 次提交
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由 Linus Torvalds 提交于
This is the mindless scripted replacement of kernel use of POLL* variables as described by Al, done by this script: for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'` for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done done with de-mangling cleanups yet to come. NOTE! On almost all architectures, the EPOLL* constants have the same values as the POLL* constants do. But they keyword here is "almost". For various bad reasons they aren't the same, and epoll() doesn't actually work quite correctly in some cases due to this on Sparc et al. The next patch from Al will sort out the final differences, and we should be all done. Scripted-by: NAl Viro <viro@zeniv.linux.org.uk> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 30 1月, 2018 1 次提交
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由 Li RongQing 提交于
socket can be disconnected and gets transformed back to a listening socket, if sk_frag.page is not released, which will be cloned into a new socket by sk_clone_lock, but the reference count of this page is increased, lead to a use after free or double free issue Signed-off-by: NLi RongQing <lirongqing@baidu.com> Cc: Eric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 26 1月, 2018 2 次提交
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由 Lawrence Brakmo 提交于
Adds support for calling sock_ops BPF program when there is a TCP state change. Two arguments are used; one for the old state and another for the new state. There is a new enum in include/uapi/linux/bpf.h that exports the TCP states that prepends BPF_ to the current TCP state names. If it is ever necessary to change the internal TCP state values (other than adding more to the end), then it will become necessary to convert from the internal TCP state value to the BPF value before calling the BPF sock_ops function. There are a set of compile checks added in tcp.c to detect if the internal and BPF values differ so we can make the necessary fixes. New op: BPF_SOCK_OPS_STATE_CB. Signed-off-by: NLawrence Brakmo <brakmo@fb.com> Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
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由 Lawrence Brakmo 提交于
Adds support for passing up to 4 arguments to sock_ops bpf functions. It reusues the reply union, so the bpf_sock_ops structures are not increased in size. Signed-off-by: NLawrence Brakmo <brakmo@fb.com> Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
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- 25 1月, 2018 1 次提交
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由 Dan Streetman 提交于
When a tcp socket is closed, if it detects that its net namespace is exiting, close immediately and do not wait for FIN sequence. For normal sockets, a reference is taken to their net namespace, so it will never exit while the socket is open. However, kernel sockets do not take a reference to their net namespace, so it may begin exiting while the kernel socket is still open. In this case if the kernel socket is a tcp socket, it will stay open trying to complete its close sequence. The sock's dst(s) hold a reference to their interface, which are all transferred to the namespace's loopback interface when the real interfaces are taken down. When the namespace tries to take down its loopback interface, it hangs waiting for all references to the loopback interface to release, which results in messages like: unregister_netdevice: waiting for lo to become free. Usage count = 1 These messages continue until the socket finally times out and closes. Since the net namespace cleanup holds the net_mutex while calling its registered pernet callbacks, any new net namespace initialization is blocked until the current net namespace finishes exiting. After this change, the tcp socket notices the exiting net namespace, and closes immediately, releasing its dst(s) and their reference to the loopback interface, which lets the net namespace continue exiting. Link: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1711407 Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=97811Signed-off-by: NDan Streetman <ddstreet@canonical.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 11 1月, 2018 1 次提交
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由 Wei Yongjun 提交于
Fixes the following sparse warning: net/ipv4/tcp.c:1736:6: warning: symbol 'tcp_recv_timestamp' was not declared. Should it be static? Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 06 1月, 2018 1 次提交
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由 Soheil Hassas Yeganeh 提交于
On multi-threaded processes, one common architecture is to have one (or a small number of) threads polling sockets, and a considerably larger pool of threads reading form and writing to the sockets. When we set RPS core on tcp_poll() or udp_poll() we essentially steer all packets of all the polled FDs to one (or small number of) cores, creaing a bottleneck and/or RPS misprediction. Another common architecture is to shard FDs among threads pinned to cores. In such a setting, setting RPS core in tcp_poll() and udp_poll() is redundant because the RFS core is correctly set in recvmsg and sendmsg. Thus, revert the following commit: c3f1dbaf ("net: Update RFS target at poll for tcp/udp"). Signed-off-by: NSoheil Hassas Yeganeh <soheil@google.com> Signed-off-by: NWillem de Bruijn <willemb@google.com> Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NNeal Cardwell <ncardwell@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 28 12月, 2017 3 次提交
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由 Willem de Bruijn 提交于
Zerocopy payload is now always stored in frags, and space for headers is reversed, so this memory is unused. Signed-off-by: NWillem de Bruijn <willemb@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Willem de Bruijn 提交于
This avoids an unnecessary copy of 1-2KB and improves tso_fragment, which has to fall back to tcp_fragment if skb->len != skb_data_len. It also avoids a surprising inconsistency in notifications: Zerocopy packets sent over loopback have their frags copied, so set SO_EE_CODE_ZEROCOPY_COPIED in the notification. But this currently does not happen for small packets, because when all data fits in the linear fragment, data is not copied in skb_orphan_frags_rx. Reported-by: NTom Deseyn <tom.deseyn@gmail.com> Signed-off-by: NWillem de Bruijn <willemb@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Willem de Bruijn 提交于
Skbs that reach MAX_SKB_FRAGS cannot be extended further. Do the same for zerocopy frags as non-zerocopy frags and set the PSH bit. This improves GRO assembly. Suggested-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NWillem de Bruijn <willemb@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 21 12月, 2017 2 次提交
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由 Yafang Shao 提交于
sk_state_load is only used by AF_INET/AF_INET6, so rename it to inet_sk_state_load and move it into inet_sock.h. sk_state_store is removed as it is not used any more. Signed-off-by: NYafang Shao <laoar.shao@gmail.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Yafang Shao 提交于
As sk_state is a common field for struct sock, so the state transition tracepoint should not be a TCP specific feature. Currently it traces all AF_INET state transition, so I rename this tracepoint to inet_sock_set_state tracepoint with some minor changes and move it into trace/events/sock.h. We dont need to create a file named trace/events/inet_sock.h for this one single tracepoint. Two helpers are introduced to trace sk_state transition - void inet_sk_state_store(struct sock *sk, int newstate); - void inet_sk_set_state(struct sock *sk, int state); As trace header should not be included in other header files, so they are defined in sock.c. The protocol such as SCTP maybe compiled as a ko, hence export inet_sk_set_state(). Signed-off-by: NYafang Shao <laoar.shao@gmail.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 08 12月, 2017 1 次提交
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由 Yousuk Seung 提交于
Mark tcp_sock during a SACK reneging event and invalidate rate samples while marked. Such rate samples may overestimate bw by including packets that were SACKed before reneging. < ack 6001 win 10000 sack 7001:38001 < ack 7001 win 0 sack 8001:38001 // Reneg detected > seq 7001:8001 // RTO, SACK cleared. < ack 38001 win 10000 In above example the rate sample taken after the last ack will count 7001-38001 as delivered while the actual delivery rate likely could be much lower i.e. 7001-8001. This patch adds a new field tcp_sock.sack_reneg and marks it when we declare SACK reneging and entering TCP_CA_Loss, and unmarks it after the last rate sample was taken before moving back to TCP_CA_Open. This patch also invalidates rate samples taken while tcp_sock.is_sack_reneg is set. Fixes: b9f64820 ("tcp: track data delivery rate for a TCP connection") Signed-off-by: NYousuk Seung <ysseung@google.com> Signed-off-by: NNeal Cardwell <ncardwell@google.com> Signed-off-by: NYuchung Cheng <ycheng@google.com> Acked-by: NSoheil Hassas Yeganeh <soheil@google.com> Acked-by: NEric Dumazet <edumazet@google.com> Acked-by: NPriyaranjan Jha <priyarjha@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 03 12月, 2017 1 次提交
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由 Martin KaFai Lau 提交于
Enable the second listener hashtable in TCP. The scale is the same as UDP which is one slot per 2MB. Signed-off-by: NMartin KaFai Lau <kafai@fb.com> Reviewed-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 28 11月, 2017 1 次提交
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由 Al Viro 提交于
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 11 11月, 2017 2 次提交
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由 Yuchung Cheng 提交于
Replace the reordering distance measurement in packet unit with sequence based approach. Previously it trackes the number of "packets" toward the forward ACK (i.e. highest sacked sequence)in a state variable "fackets_out". Precisely measuring reordering degree on packet distance has not much benefit, as the degree constantly changes by factors like path, load, and congestion window. It is also complicated and prone to arcane bugs. This patch replaces with sequence-based approach that's much simpler. Signed-off-by: NYuchung Cheng <ycheng@google.com> Reviewed-by: NEric Dumazet <edumazet@google.com> Reviewed-by: NNeal Cardwell <ncardwell@google.com> Reviewed-by: NSoheil Hassas Yeganeh <soheil@google.com> Reviewed-by: NPriyaranjan Jha <priyarjha@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Yuchung Cheng 提交于
FACK loss detection has been disabled by default and the successor RACK subsumed FACK and can handle reordering better. This patch removes FACK to simplify TCP loss recovery. Signed-off-by: NYuchung Cheng <ycheng@google.com> Reviewed-by: NEric Dumazet <edumazet@google.com> Reviewed-by: NNeal Cardwell <ncardwell@google.com> Reviewed-by: NSoheil Hassas Yeganeh <soheil@google.com> Reviewed-by: NPriyaranjan Jha <priyarjha@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 10 11月, 2017 1 次提交
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由 Eric Dumazet 提交于
Note that when a new netns is created, it inherits its sysctl_tcp_rmem and sysctl_tcp_wmem from initial netns. This change is needed so that we can refine TCP rcvbuf autotuning, to take RTT into consideration. Signed-off-by: NEric Dumazet <edumazet@google.com> Cc: Wei Wang <weiwan@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 05 11月, 2017 1 次提交
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由 Priyaranjan Jha 提交于
Currently TCP RACK loss detection does not work well if packets are being reordered beyond its static reordering window (min_rtt/4).Under such reordering it may falsely trigger loss recoveries and reduce TCP throughput significantly. This patch improves that by increasing and reducing the reordering window based on DSACK, which is now supported in major TCP implementations. It makes RACK's reo_wnd adaptive based on DSACK and no. of recoveries. - If DSACK is received, increment reo_wnd by min_rtt/4 (upper bounded by srtt), since there is possibility that spurious retransmission was due to reordering delay longer than reo_wnd. - Persist the current reo_wnd value for TCP_RACK_RECOVERY_THRESH (16) no. of successful recoveries (accounts for full DSACK-based loss recovery undo). After that, reset it to default (min_rtt/4). - At max, reo_wnd is incremented only once per rtt. So that the new DSACK on which we are reacting, is due to the spurious retx (approx) after the reo_wnd has been updated last time. - reo_wnd is tracked in terms of steps (of min_rtt/4), rather than absolute value to account for change in rtt. In our internal testing, we observed significant increase in throughput, in scenarios where reordering exceeds min_rtt/4 (previous static value). Signed-off-by: NPriyaranjan Jha <priyarjha@google.com> Signed-off-by: NYuchung Cheng <ycheng@google.com> Signed-off-by: NNeal Cardwell <ncardwell@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 28 10月, 2017 2 次提交
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由 Eric Dumazet 提交于
Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Eric Dumazet 提交于
Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 27 10月, 2017 1 次提交
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由 Eric Dumazet 提交于
Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 26 10月, 2017 1 次提交
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由 Ursula Braun 提交于
The SMC protocol [1] relies on the use of a new TCP experimental option [2, 3]. With this option, SMC capabilities are exchanged between peers during the TCP three way handshake. This patch adds support for this experimental option to TCP. References: [1] SMC-R Informational RFC: http://www.rfc-editor.org/info/rfc7609 [2] Shared Use of TCP Experimental Options RFC 6994: https://tools.ietf.org/rfc/rfc6994.txt [3] IANA ExID SMCR: http://www.iana.org/assignments/tcp-parameters/tcp-parameters.xhtml#tcp-exidsSigned-off-by: NUrsula Braun <ubraun@linux.vnet.ibm.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 24 10月, 2017 2 次提交
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由 Christoph Paasch 提交于
We already allow to enable TFO without a cookie by using the fastopen-sysctl and setting it to TFO_SERVER_COOKIE_NOT_REQD (or TFO_CLIENT_NO_COOKIE). This is safe to do in certain environments where we know that there isn't a malicous host (aka., data-centers) or when the application-protocol already provides an authentication mechanism in the first flight of data. A server however might be providing multiple services or talking to both sides (public Internet and data-center). So, this server would want to enable cookie-less TFO for certain services and/or for connections that go to the data-center. This patch exposes a socket-option and a per-route attribute to enable such fine-grained configurations. Signed-off-by: NChristoph Paasch <cpaasch@apple.com> Reviewed-by: NYuchung Cheng <ycheng@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Song Liu 提交于
This patch adds tracepoint trace_tcp_set_state. Besides usual fields (s/d ports, IP addresses), old and new state of the socket is also printed with TP_printk, with __print_symbolic(). Signed-off-by: NSong Liu <songliubraving@fb.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 20 10月, 2017 1 次提交
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由 Yuchung Cheng 提交于
New socket option TCP_FASTOPEN_KEY to allow different keys per listener. The listener by default uses the global key until the socket option is set. The key is a 16 bytes long binary data. This option has no effect on regular non-listener TCP sockets. Signed-off-by: NYuchung Cheng <ycheng@google.com> Reviewed-by: NEric Dumazet <edumazet@google.com> Reviewed-by: NChristoph Paasch <cpaasch@apple.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 07 10月, 2017 3 次提交
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由 Eric Dumazet 提交于
Using a linear list to store all skbs in write queue has been okay for quite a while : O(N) is not too bad when N < 500. Things get messy when N is the order of 100,000 : Modern TCP stacks want 10Gbit+ of throughput even with 200 ms RTT flows. 40 ns per cache line miss means a full scan can use 4 ms, blowing away CPU caches. SACK processing often can use various hints to avoid parsing whole retransmit queue. But with high packet losses and/or high reordering, hints no longer work. Sender has to process thousands of unfriendly SACK, accumulating a huge socket backlog, burning a cpu and massively dropping packets. Using an rb-tree for retransmit queue has been avoided for years because it added complexity and overhead, but now is the time to be more resistant and say no to quadratic behavior. 1) RTX queue is no longer part of the write queue : already sent skbs are stored in one rb-tree. 2) Since reaching the head of write queue no longer needs sk->sk_send_head, we added an union of sk_send_head and tcp_rtx_queue Tested: On receiver : netem on ingress : delay 150ms 200us loss 1 GRO disabled to force stress and SACK storms. for f in `seq 1 10` do ./netperf -H lpaa6 -l30 -- -K bbr -o THROUGHPUT|tail -1 done | awk '{print $0} {sum += $0} END {printf "%7u\n",sum}' Before patch : 323.87 351.48 339.59 338.62 306.72 204.07 304.93 291.88 202.47 176.88 2840 After patch: 1700.83 2207.98 2070.17 1544.26 2114.76 2124.89 1693.14 1080.91 2216.82 1299.94 18053 Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Eric Dumazet 提交于
tcp_write_queue_tail() call can be factorized. Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 Eric Dumazet 提交于
Since the upcoming rtx rbtree will add some extra code, it is time to not inline this fat function anymore. Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 06 10月, 2017 1 次提交
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由 Eric Dumazet 提交于
This patch adds a new queue (list) that tracks the sent but not yet acked or SACKed skbs for a TCP connection. The list is chronologically ordered by skb->skb_mstamp (the head is the oldest sent skb). This list will be used to optimize TCP Rack recovery, which checks an skb's timestamp to judge if it has been lost and needs to be retransmitted. Since TCP write queue is ordered by sequence instead of sent time, RACK has to scan over the write queue to catch all eligible packets to detect lost retransmission, and iterates through SACKed skbs repeatedly. Special cares for rare events: 1. TCP repair fakes skb transmission so the send queue needs adjusted 2. SACK reneging would require re-inserting SACKed skbs into the send queue. For now I believe it's not worth the complexity to make RACK work perfectly on SACK reneging, so we do nothing here. 3. Fast Open: currently for non-TFO, send-queue correctly queues the pure SYN packet. For TFO which queues a pure SYN and then a data packet, send-queue only queues the data packet but not the pure SYN due to the structure of TFO code. This is okay because the SYN receiver would never respond with a SACK on a missing SYN (i.e. SYN is never fast-retransmitted by SACK/RACK). In order to not grow sk_buff, we use an union for the new list and _skb_refdst/destructor fields. This is a bit complicated because we need to make sure _skb_refdst and destructor are properly zeroed before skb is cloned/copied at transmit, and before being freed. Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NYuchung Cheng <ycheng@google.com> Signed-off-by: NNeal Cardwell <ncardwell@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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