Hi Andy,
> On Dec 23, 2017, at 00:38, Andy Furniss <[email protected]> wrote: > > Jonathan Morton wrote: >>> On 21 Dec, 2017, at 2:54 am, Andy Furniss <[email protected]> wrote: >>> >>> refactor cake_advance_shaper and ack_filter >>> >>> cake_advance_shaper now returns a modified len argument to >>> reflect cake_overhead. >>> skb_ack_filter variable replaced with ack >> Fixed. At one point cake_advance_shaper() was still getting a packet length >> with overhead correction already applied, and was then applying it a second >> time. > > Thanks, seems good now, well, as it was before anyway :-) > > Still a bit confusing for users having to look at max_len in stats to judge > what overhead to use if they know what over ip they want. > > Maybe some hint in the man page about turn off gro and look at max_len would > help when using raw. > > IIRC this was discussed before, I think conclusion was it's the kernel/ppp > being different/wrong sometimes in what it reports to cake. > > My specific case is pppoe where I need IP + 34. I can see 1500 as max_len, > which = IP length so raw overhead 34 is correct. > > On a pure eth to get the same I need raw overhead 20 as max_len is 1514. > > This is the (confusing) output from pppoe > > ./tc qdisc add dev ppp0 handle 1:0 root cake bandwidth 19690kbit raw overhead > 34 diffserv4 dual-srchost nat rtt 200ms > > qdisc cake 1: dev ppp0 root refcnt 2 bandwidth 19690Kbit diffserv4 > dual-srchost nat rtt 200.0ms noatm overhead 56 via-ethernet total_overhead 56 > hard_header_len 22 This is still broken, the overhead the should just be 34, and hard_header_len should be 0, even though for pppoe 22 is not completely wrong (14 + 8). I currently see the same with PPPoE+VLAN I get 26. So either that is a change in current cake or the kernel actually started to report a more precise hard_header_len... > Sent 776346756 bytes 883288 pkt (dropped 284882, overlimits 1429302 requeues > 0) > backlog 0b 0p requeues 0 > memory used: 4196096b of 4Mb > capacity estimate: 19690Kbit > Bulk Best Effort Video Voice > thresh 1230Kbit 19690Kbit 9845Kbit 4922Kbit > target 14.8ms 10.0ms 10.0ms 10.0ms > interval 204.8ms 200.0ms 200.0ms 200.0ms > pk_delay 186us 1.6ms 0us 112us > av_delay 11us 94us 0us 4us > sp_delay 1us 4us 0us 4us > pkts 1160 1166876 0 134 > bytes 457795 1202631653 0 10176 > way_inds 0 3813 0 0 > way_miss 1126 10503 0 3 > way_cols 0 0 0 0 > drops 0 284882 0 0 > marks 0 0 0 0 > ack_drop 0 0 0 0 > sp_flows 0 1 0 0 > bk_flows 0 1 0 0 > un_flows 0 0 0 0 > max_len 746 1500 0 76 > > > > On eth raw overhead 34 gives different results, only seeing max_len gives the > clue to take 14 to get IP + 34. > > tc qdisc add dev enp6s0 handle 1:0 root cake bandwidth 19690kbit raw overhead > 34 > > qdisc cake 1: dev enp6s0 root refcnt 2 bandwidth 19690Kbit diffserv3 > triple-isolate rtt 100.0ms noatm overhead 48 via-ethernet total_overhead 48 > hard_header_len 14 This looks like expected, the in-kernel overhead is added to the specified overhead, just like in the past. I really really wished cake would report the packet size before and _after_ its overhead addition making sanity checking much easier. BTW tc's stab might be useful as an external check... I also wonder whether the kernel's behaviour in regards to ppp interfaces changed between kernel 4.4 and newer ones, I see the same weirdness: root@router:~# uname -a Linux router 4.9.67 #0 Sun Dec 17 11:53:32 2017 mips GNU/Linux excerpt from tc -s: qdisc cake 800f: dev pppoe-wan root refcnt 2 bandwidth 9545Kbit diffserv3 dual-srchost nat rtt 100.0ms noatm overhead 34 via-ethernet total_overhead 34 hard_header_len 26 mpu 64 I note that hard_header_len 26 sort of matches the situation on the ground: Mine: 14 (SRCMAC, DSTMAC, ethertype) + 8 (PPP, PPPOE), + 4 (VLAN) = 26 Yours: 14 (SRCMAC, DSTMAC, ethertype) + 8 (PPP, PPPOE) = 22 I guess I should try with different kernels and recent sch_cake... Best Regards Sebastian > Sent 24102094 bytes 15934 pkt (dropped 1, overlimits 31841 requeues 0) > backlog 0b 0p requeues 0 > memory used: 27Kb of 4Mb > capacity estimate: 19690Kbit > Bulk Best Effort Voice > thresh 1230Kbit 19690Kbit 4922Kbit > target 14.8ms 5.0ms 5.0ms > interval 109.8ms 100.0ms 100.0ms > pk_delay 0us 1.7ms 0us > av_delay 0us 1.7ms 0us > sp_delay 0us 229us 0us > pkts 0 15935 0 > bytes 0 24103608 0 > way_inds 0 0 0 > way_miss 0 4 0 > way_cols 0 0 0 > drops 0 1 0 > marks 0 0 0 > ack_drop 0 0 0 > sp_flows 0 0 0 > bk_flows 0 1 0 > un_flows 0 0 0 > max_len 0 1514 0 > _______________________________________________ > Cake mailing list > [email protected] > https://lists.bufferbloat.net/listinfo/cake _______________________________________________ Cake mailing list [email protected] https://lists.bufferbloat.net/listinfo/cake
