- 17 Jan, 2017 5 commits
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Philippe Reynes authored
The ethtool api {get|set}_settings is deprecated. We move this driver to new api {get|set}_link_ksettings. As I don't have the hardware, I'd be very pleased if someone may test this patch. Signed-off-by: Philippe Reynes <tremyfr@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Philippe Reynes authored
The ethtool api {get|set}_settings is deprecated. We move this driver to new api {get|set}_link_ksettings. Signed-off-by: Philippe Reynes <tremyfr@gmail.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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David S. Miller authored
Marcin Wojtas says: ==================== mvneta xmit_more and bql support This is a delayed v2 of short patchset, which introduces xmit_more and BQL to mvneta driver. The only one change was added in xmit_more support - condition check preventing excessive descriptors concatenation before flushing in HW. Any comments or feedback would be welcome. Changelog: v1 -> v2: * Add checking condition that ensures too much descriptors are not concatenated before flushing in HW. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
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Marcin Wojtas authored
Tests showed that when whole bandwidth is consumed, the latency for various kind of traffic can reach high values. With saturated link (e.g. with iperf from target to host) simple ping could take significant amount of time. BQL proved to improve this situation when implemented in mvneta driver. Measurements of ping latency for 3 link speeds: Speed | Latency w/o BQL | Latency with BQL 10 | 7-14 ms | 3.5 ms 100 | 2-12 ms | 0.6 ms 1000 | often timeout | up to 2ms Decreasing latency as above result in sligt performance cost - 4kpps (-1.4%) when pushing 64B packets via two bridged interfaces of Armada 38x. For 1500B packets in the same setup, the mpstat tool showed +8% of CPU occupation (default affinity, second CPU idle). Even though this cost seems reasonable to take, considering other improvements. This commit adds byte queue limit mechanism for the mvneta driver. Signed-off-by: Marcin Wojtas <mw@semihalf.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Simon Guinot authored
Basing on xmit_more flag of the skb, TX descriptors can be concatenated before flushing. This commit delay Tx descriptor flush if the queue is running and if there is more skb's to send. A maximum allowed number of descriptors for flushing at once due to MVNETA_TXQ_UPDATE_REG(q) reqisters limitation, is 255. Because of that a new macro was added (MVNETA_TXQ_DEC_SENT_MASK) in order to ensure that concatenated amount of descriptor does not exceed that value. Signed-off-by: Simon Guinot <simon.guinot@sequanux.org> Signed-off-by: Marcin Wojtas <mw@semihalf.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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- 16 Jan, 2017 15 commits
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Paul Blakey authored
Flower currently allows having the same filter twice with the same priority. Actions (and statistics update) will always execute on the first inserted rule leaving the second rule unused. This patch disallows that. Signed-off-by: Paul Blakey <paulb@mellanox.com> Acked-by: Jiri Pirko <jiri@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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David Lebrun authored
Add missing IPv6-SR header files in include/uapi/linux/Kbuild. Also, prevent seg6_lwt_headroom() from being exported and add missing linux/types.h include. Signed-off-by: David Lebrun <david.lebrun@uclouvain.be> Signed-off-by: David S. Miller <davem@davemloft.net>
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Daniel Borkmann authored
Make sure that ctx cannot potentially be accessed oob by asserting explicitly that ctx access size into pt_regs for BPF_PROG_TYPE_KPROBE programs must be within limits. In case some 32bit archs have pt_regs not being a multiple of 8, then BPF_DW access could cause such access. BPF_PROG_TYPE_KPROBE progs don't have a ctx conversion function since there's no extra mapping needed. kprobe_prog_is_valid_access() didn't enforce sizeof(long) as the only allowed access size, since LLVM can generate non BPF_W/BPF_DW access to regs from time to time. For BPF_PROG_TYPE_TRACEPOINT we don't have a ctx conversion either, so add a BUILD_BUG_ON() check to make sure that BPF_DW access will not be a similar issue in future (ctx works on event buffer as opposed to pt_regs there). Fixes: 2541517c ("tracing, perf: Implement BPF programs attached to kprobes") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
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Mahesh Bandewar authored
In the last patch da36e13c ("ipvlan: improvise dev_id generation logic in IPvlan") I missed some part of Dave's suggestion and because of that the dev_id creation could fail in a corner case scenario. This would happen when more or less 64k devices have been already created and several have been deleted. If the devices that are still sticking around are the last n bits from the bitmap. So in this scenario even if lower bits are available, the dev_id search is so narrow that it always fails. Fixes: da36e13c ("ipvlan: improvise dev_id generation logic in IPvlan") CC: David Miller <davem@davemloft.org> CC: Eric Dumazet <edumazet@google.com> Signed-off-by: Mahesh Bandewar <maheshb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Edward Cree authored
The 8000 series SFC NICs have 4K PIO buffers, rather than the 2K of the 7000 series. Rather than having a hard-coded PIO buffer size (ER_DZ_TX_PIOBUF_SIZE), read it from the GET_CAPABILITIES_V2 MCDI response. Signed-off-by: Edward Cree <ecree@solarflare.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Edward Cree authored
If an option descriptor has been sent on a queue but not followed by a packet, there will have been no completion event, so the read and write counts won't match and we'll think we can't do PIO. This combines with the fact that we have two TX queues (for en/disable checksum offload), and that both must be empty for PIO to happen. This patch adds a separate "packet_write_count" that tracks the most recent write_count we expect to see a completion event for; this excludes option descriptors but _includes_ PIO descriptors (even though they look like option descriptors). This is then used, rather than write_count, in efx_nic_tx_is_empty(). We only bother to maintain packet_write_count on EF10, since on Siena (a) there are no option descriptors and it always equals write_count, and (b) there's no PIO, so we don't need it anyway. Signed-off-by: Edward Cree <ecree@solarflare.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Marcelo Ricardo Leitner authored
sctp_frag_point() doesn't store anything, and thus just calling it cannot do anything useful. sctp_apply_peer_addr_params is only called by sctp_setsockopt_peer_addr_params. When operating on an asoc, sctp_setsockopt_peer_addr_params will call sctp_apply_peer_addr_params once for the asoc, and then once for each transport this asoc has, meaning that the frag_point will be recomputed when updating the transports and calling it when updating the asoc is not necessary. IOW, no action is needed here and we can remove this call. Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Acked-by: Neil Horman <nhorman@tuxdriver.com> Reviewed-by: Xin Long <lucien.xin@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Marcelo Ricardo Leitner authored
Assigned but not used. Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Acked-by: Neil Horman <nhorman@tuxdriver.com> Reviewed-by: Xin Long <lucien.xin@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Colin Ian King authored
arp is being checked instead of arp_eth to see if the call to __skb_header_pointer failed. Fix this by checking arp_eth is null instead of arp. Also fix to use length hlen rather than hlen - sizeof(_arp); thanks to Eric Dumazet for spotting this latter issue. CoverityScan CID#1396428 ("Logically dead code") on 2nd arp comparison (which should be arp_eth instead). Fixes: commit 55733350 ("flow disector: ARP support") Signed-off-by: Colin Ian King <colin.king@canonical.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Eric Dumazet authored
In commit d35c99ff ("netlink: do not enter direct reclaim from netlink_dump()") we made sure to not trigger expensive memory reclaim. Problem is that a bit later, netlink_trim() might be called and trigger memory reclaim. netlink_trim() should be best effort, and really as fast as possible. Under memory pressure, it is fine to not trim this skb. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
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Hariprasad Shenai authored
Perform an emergency shutdown of the adapter and stop it from continuing any further communication on the ports or DMA to the host. This is typically used when the adapter and/or firmware have crashed and we want to prevent any further accidental communication with the rest of the world. This will also force the port Link Status to go down -- if register writes work -- which should help our peers figure out that we're down. Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Arnd Bergmann authored
The bulk readpages support introduced a harmless warning: fs/afs/file.c: In function 'afs_readpages_page_done': fs/afs/file.c:270:20: error: unused variable 'vnode' [-Werror=unused-variable] This adds an #ifdef to match the user of that variable. The user of the variable has to be conditional because it accesses a member of a struct that is also conditional. Fixes: 91b467e0 ("afs: Make afs_readpages() fetch data in bulk") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Shyam Saini authored
Use eth_zero_addr to assign zero address to the given address array instead of memset when the second argument in memset is address of zero which makes the code clearer and also add header file linux/etherdevice.h Signed-off-by: Shyam Saini <mayhs11saini@gmail.com> Acked-by: Edward Cree <ecree@solarflare.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Dan Carpenter authored
The break statement should be indented one more tab. Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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jpinto authored
This driver is no longer necessary since it was merged into stmmac. Acked-by: Lars Persson <larper@axis.com> Signed-off-by: Joao Pinto <jpinto@synopsys.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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- 14 Jan, 2017 20 commits
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David S. Miller authored
Merge tag 'mac80211-next-for-davem-2017-01-13' of git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next Johannes Berg says: ==================== For 4.11, we seem to have more than in the past few releases: * socket owner support for connections, so when the wifi manager (e.g. wpa_supplicant) is killed, connections are torn down - wpa_supplicant is critical to managing certain operations, and can opt in to this where applicable * minstrel & minstrel_ht updates to be more efficient (time and space) * set wifi_acked/wifi_acked_valid for skb->destructor use in the kernel, which was already available to userspace * don't indicate new mesh peers that might be used if there's no room to add them * multicast-to-unicast support in mac80211, for better medium usage (since unicast frames can use *much* higher rates, by ~3 orders of magnitude) * add API to read channel (frequency) limitations from DT * add infrastructure to allow randomizing public action frames for MAC address privacy (still requires driver support) * many cleanups and small improvements/fixes across the board ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
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Shyam Saini authored
The region set by the call to memset, immediately overwritten by the subsequent call to memcpy and thus makes the memset redundant. Also remove the memset((&info, 0, sizeof(info)) on line 398 because info is memcpy()'ed to before being used in the loop and it isn't used outside of the loop. Signed-off-by: Shyam Saini <mayhs11saini@gmail.com> Reviewed-by: Tobias Klauser <tklauser@distanz.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
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Ganesh Goudar authored
Do not count pause frames as part of general TX/RX frame counters. Based on the original work of Casey Leedom <leedom@chelsio.com> Signed-off-by: Ganesh Goudar <ganeshgr@chelsio.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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David S. Miller authored
Michael Chan says: ==================== bnxt_en: Misc. updates for net-next. Miscellaneous updates including firmware spec update, ethtool -p blinking LED support, RDMA SRIOV config callback, and minor fixes. v2: Dropped the DCBX RoCE app TLV patch until the ETH_P_IBOE RDMA patch is merged. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
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Michael Chan authored
Add the ulp_sriov_cfg callbacks when the number of VFs is changing. This allows the RDMA driver to provision RDMA resources for the VFs. Signed-off-by: Michael Chan <michael.chan@broadcom.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Michael Chan authored
Add LED blinking code to support ethtool -p on the PF. Signed-off-by: Michael Chan <michael.chan@broadcom.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Michael Chan authored
Signed-off-by: Michael Chan <michael.chan@broadcom.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Michael Chan authored
Commit bdbd1eb5 ("bnxt_en: Handle no aggregation ring gracefully.") introduced the BNXT_FLAG_NO_AGG_RINGS flag. For consistency, bnxt_set_tpa_flags() should also clear TPA flags when there are no aggregation rings. Signed-off-by: Michael Chan <michael.chan@broadcom.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Michael Chan authored
CC [M] drivers/net/ethernet/broadcom/bnxt/bnxt.o drivers/net/ethernet/broadcom/bnxt/bnxt.c:4947:21: warning: ‘bnxt_get_max_func_rss_ctxs’ defined but not used [-Wunused-function] static unsigned int bnxt_get_max_func_rss_ctxs(struct bnxt *bp) ^ CC [M] drivers/net/ethernet/broadcom/bnxt/bnxt.o drivers/net/ethernet/broadcom/bnxt/bnxt.c:4956:21: warning: ‘bnxt_get_max_func_vnics’ defined but not used [-Wunused-function] static unsigned int bnxt_get_max_func_vnics(struct bnxt *bp) ^ Signed-off-by: Michael Chan <michael.chan@broadcom.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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David S. Miller authored
Yuchung Cheng says: ==================== tcp: RACK fast recovery The patch set enables RACK loss detection (draft-ietf-tcpm-rack-01) to trigger fast recovery with a reordering timer. Previously RACK has been running in auxiliary mode where it is used to detect packet losses once the recovery has triggered by other algorithms (e.g., FACK). By inspecting packet timestamps, RACK can start ACK-driven repairs timely. A few similar heuristics are no longer needed and are either removed or disabled to reduce the complexity of the Linux TCP loss recovery engine: 1. FACK (Forward Acknowledgement) 2. Early Retransmit (RFC5827) 3. thin_dupack (fast recovery on single DUPACK for thin-streams) 4. NCR (Non-Congestion Robustness RFC4653) (RFC4653) 5. Forward Retransmit After this change, Linux's loss recovery algorithms consist of 1. Conventional DUPACK threshold approach (RFC6675) 2. RACK and Tail Loss Probe (draft-ietf-tcpm-rack-01) 3. RTO plus F-RTO extension (RFC5682) The patch set has been tested on Google servers extensively and presented in several IETF meetings. The data suggests that RACK successfully improves recovery performance: https://www.ietf.org/proceedings/97/slides/slides-97-tcpm-draft-ietf-tcpm-rack-01.pdf https://www.ietf.org/proceedings/96/slides/slides-96-tcpm-3.pdf ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
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Yuchung Cheng authored
This patch disables FACK by default as RACK is the successor of FACK (inspired by the insights behind FACK). FACK[1] in Linux works as follows: a packet P is deemed lost, if packet Q of higher sequence is s/acked and P and Q are distant by at least dupthresh number of packets in sequence space. FACK is more aggressive than the IETF recommened recovery for SACK (RFC3517 A Conservative Selective Acknowledgment (SACK)-based Loss Recovery Algorithm for TCP), because a single SACK may trigger fast recovery. This obviously won't work well with reordering so FACK is dynamically disabled upon detecting reordering. RACK supersedes FACK by using time distance instead of sequence distance. On reordering, RACK waits for a quarter of RTT receiving a single SACK before starting recovery. (the timer can be made more adaptive in the future by measuring reordering distance in time, but currently RTT/4 seem to work well.) Once the recovery starts, RACK behaves almost like FACK because it reduces the reodering window to 1ms, so it fast retransmits quickly. In addition RACK can detect loss retransmission as it does not care about the packet sequences (being repeated or not), which is extremely useful when the connection is going through a traffic policer. Google server experiments indicate that disabling FACK after enabling RACK has negligible impact on the overall loss recovery performance with more reordering events detected. But we still keep the FACK implementation for backup if RACK has bugs that needs to be disabled. [1] M. Mathis, J. Mahdavi, "Forward Acknowledgment: Refining TCP Congestion Control," In Proceedings of SIGCOMM '96, August 1996. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Yuchung Cheng authored
Thin stream DUPACK is to start fast recovery on only one DUPACK provided the connection is a thin stream (i.e., low inflight). But this older feature is now subsumed with RACK. If a connection receives only a single DUPACK, RACK would arm a reordering timer and soon starts fast recovery instead of timeout if no further ACKs are received. The socket option (THIN_DUPACK) is kept as a nop for compatibility. Note that this patch does not change another thin-stream feature which enables linear RTO. Although it might be good to generalize that in the future (i.e., linear RTO for the first say 3 retries). Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Yuchung Cheng authored
This patch removes the (partial) implementation of the aggressive limited transmit in RFC4653 TCP Non-Congestion Robustness (NCR). NCR is a mitigation to the problem created by the dynamic DUPACK threshold. With the current adaptive DUPACK threshold (tp->reordering) could cause timeouts by preventing fast recovery. For example, if the last packet of a cwnd burst was reordered, the threshold will be set to the size of cwnd. But if next application burst is smaller than threshold and has drops instead of reorderings, the sender would not trigger fast recovery but instead resorts to a timeout recovery. NCR mitigates this issue by checking the number of DUPACKs against the current flight size additionally. The techniqueue is similar to the early retransmit RFC. With RACK loss detection, this mitigation is not needed, because RACK does not use DUPACK threshold to detect losses. RACK arms a reordering timer to fire at most a quarter RTT later to start fast recovery. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Yuchung Cheng authored
This patch removes the support of RFC5827 early retransmit (i.e., fast recovery on small inflight with <3 dupacks) because it is subsumed by the new RACK loss detection. More specifically when RACK receives DUPACKs, it'll arm a reordering timer to start fast recovery after a quarter of (min)RTT, hence it covers the early retransmit except RACK does not limit itself to specific inflight or dupack numbers. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Yuchung Cheng authored
Forward retransmit is an esoteric feature in RFC3517 (condition(3) in the NextSeg()). Basically if a packet is not considered lost by the current criteria (# of dupacks etc), but the congestion window has room for more packets, then retransmit this packet. However it actually conflicts with the rest of recovery design. For example, when reordering is detected we want to be conservative in retransmitting packets but forward-retransmit feature would break that to force more retransmission. Also the implementation is fairly complicated inside the retransmission logic inducing extra iterations in the write queue. With RACK losses are being detected timely and this heuristic is no longer necessary. There this patch removes the feature. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Yuchung Cheng authored
Current F-RTO reverts cwnd reset whenever a never-retransmitted packet was (s)acked. The timeout can be declared spurious because the packets acknoledged with this ACK was transmitted before the timeout, so clearly not all the packets are lost to reset the cwnd. This nice detection does not really depend F-RTO internals. This patch applies the detection universally. On Google servers this change detected 20% more spurious timeouts. Suggested-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Yuchung Cheng authored
This patch changes two things: 1. Start fast recovery with RACK in addition to other heuristics (e.g., DUPACK threshold, FACK). Prior to this change RACK is enabled to detect losses only after the recovery has started by other algorithms. 2. Disable TCP early retransmit. RACK subsumes the early retransmit with the new reordering timer feature. A latter patch in this series removes the early retransmit code. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Yuchung Cheng authored
Currently RACK would mark loss before the undo operations in TCP loss recovery. This could incorrectly identify real losses as spurious. For example a sender first experiences a delay spike and then eventually some packets were lost due to buffer overrun. In this case, the sender should perform fast recovery b/c not all the packets were lost. But the sender may first trigger a (spurious) RTO and reset cwnd to 1. The following ACKs may used to mark real losses by tcp_rack_mark_lost. Then in tcp_process_loss this ACK could trigger F-RTO undo condition and unmark real losses and revert the cwnd reduction. If there are no more ACKs coming back, eventually the sender would timeout again instead of performing fast recovery. The patch fixes this incorrect process by always performing the undo checks before detecting losses. Fixes: 4f41b1c5 ("tcp: use RACK to detect losses") Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Yuchung Cheng authored
The packets inside a jumbo skb (e.g., TSO) share the same skb timestamp, even though they are sent sequentially on the wire. Since RACK is based on time, it can not detect some packets inside the same skb are lost. However, we can leverage the packet sequence numbers as extended timestamps to detect losses. Therefore, when RACK timestamp is identical to skb's timestamp (i.e., one of the packets of the skb is acked or sacked), we use the sequence numbers of the acked and unacked packets to break ties. We can use the same sequence logic to advance RACK xmit time as well to detect more losses and avoid timeout. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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Yuchung Cheng authored
This patch makes RACK install a reordering timer when it suspects some packets might be lost, but wants to delay the decision a little bit to accomodate reordering. It does not create a new timer but instead repurposes the existing RTO timer, because both are meant to retransmit packets. Specifically it arms a timer ICSK_TIME_REO_TIMEOUT when the RACK timing check fails. The wait time is set to RACK.RTT + RACK.reo_wnd - (NOW - Packet.xmit_time) + fudge This translates to expecting a packet (Packet) should take (RACK.RTT + RACK.reo_wnd + fudge) to deliver after it was sent. When there are multiple packets that need a timer, we use one timer with the maximum timeout. Therefore the timer conservatively uses the maximum window to expire N packets by one timeout, instead of N timeouts to expire N packets sent at different times. The fudge factor is 2 jiffies to ensure when the timer fires, all the suspected packets would exceed the deadline and be marked lost by tcp_rack_detect_loss(). It has to be at least 1 jiffy because the clock may tick between calling icsk_reset_xmit_timer(timeout) and actually hang the timer. The next jiffy is to lower-bound the timeout to 2 jiffies when reo_wnd is < 1ms. When the reordering timer fires (tcp_rack_reo_timeout): If we aren't in Recovery we'll enter fast recovery and force fast retransmit. This is very similar to the early retransmit (RFC5827) except RACK is not constrained to only enter recovery for small outstanding flights. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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