On Fri, May 6, 2016 at 11:56 AM, Roman Yeryomin <leroi.li...@gmail.com> wrote: > On 6 May 2016 at 21:43, Roman Yeryomin <leroi.li...@gmail.com> wrote: >> On 6 May 2016 at 15:47, Jesper Dangaard Brouer <bro...@redhat.com> wrote: >>> >>> I've created a OpenWRT ticket[1] on this issue, as it seems that someone[2] >>> closed Felix'es OpenWRT email account (bad choice! emails bouncing). >>> Sounds like OpenWRT and the LEDE https://www.lede-project.org/ project >>> is in some kind of conflict. >>> >>> OpenWRT ticket [1] https://dev.openwrt.org/ticket/22349 >>> >>> [2] >>> http://thread.gmane.org/gmane.comp.embedded.openwrt.devel/40298/focus=40335 >> >> OK, so, after porting the patch to 4.1 openwrt kernel and playing a >> bit with fq_codel limits I was able to get 420Mbps UDP like this: >> tc qdisc replace dev wlan0 parent :1 fq_codel flows 16 limit 256 > > Forgot to mention, I've reduced drop_batch_size down to 32
0) Not clear to me if that's the right line, there are 4 wifi queues, and the third one is the BE queue. That is too low a limit, also, for normal use. And: for the purpose of this particular UDP test, flows 16 is ok, but not ideal. 1) What's the tcp number (with a simultaneous ping) with this latest patchset? (I care about tcp performance a lot more than udp floods - surviving a udp flood yes, performance, no) before/after? tc -s qdisc show dev wlan0 during/after results? IF you are doing builds for the archer c7v2, I can join in on this... (?) I did do a test of the ath10k "before", fq_codel *never engaged*, and tcp induced latencies under load, e at 100mbit, cracked 600ms, while staying flat (20ms) at 100mbit. (not the same patches you are testing) on x86. I have got tcp 300Mbit out of an osx box, similar latency, have yet to get anything more on anything I currently have before/after patchsets. I'll go add flooding to the tests, I just finished a series comparing two different speed stations and life was good on that. "before" - fq_codel never engages, we see seconds of latency under load. root@apu2:~# tc -s qdisc show dev wlp4s0 qdisc mq 0: root Sent 8570563893 bytes 6326983 pkt (dropped 0, overlimits 0 requeues 0) backlog 0b 0p requeues 0 qdisc fq_codel 0: parent :1 limit 10240p flows 1024 quantum 1514 target 5.0ms interval 100.0ms ecn Sent 2262 bytes 17 pkt (dropped 0, overlimits 0 requeues 0) backlog 0b 0p requeues 0 maxpacket 0 drop_overlimit 0 new_flow_count 0 ecn_mark 0 new_flows_len 0 old_flows_len 0 qdisc fq_codel 0: parent :2 limit 10240p flows 1024 quantum 1514 target 5.0ms interval 100.0ms ecn Sent 220486569 bytes 152058 pkt (dropped 0, overlimits 0 requeues 0) backlog 0b 0p requeues 0 maxpacket 18168 drop_overlimit 0 new_flow_count 1 ecn_mark 0 new_flows_len 0 old_flows_len 1 qdisc fq_codel 0: parent :3 limit 10240p flows 1024 quantum 1514 target 5.0ms interval 100.0ms ecn Sent 8340546509 bytes 6163431 pkt (dropped 0, overlimits 0 requeues 0) backlog 0b 0p requeues 0 maxpacket 68130 drop_overlimit 0 new_flow_count 120050 ecn_mark 0 new_flows_len 1 old_flows_len 3 qdisc fq_codel 0: parent :4 limit 10240p flows 1024 quantum 1514 target 5.0ms interval 100.0ms ecn Sent 9528553 bytes 11477 pkt (dropped 0, overlimits 0 requeues 0) backlog 0b 0p requeues 0 maxpacket 66 drop_overlimit 0 new_flow_count 1 ecn_mark 0 new_flows_len 1 old_flows_len 0 ``` >> This is certainly better than 30Mbps but still more than two times >> less than before (900). The number that I still am not sure we got is that you were sending 900mbit udp and recieving 900mbit on the prior tests? >> TCP also improved a little (550 to ~590). The limit is probably a bit low, also. You might want to try target 20ms as well. >> >> Felix, others, do you want to see the ported patch, maybe I did something >> wrong? >> Doesn't look like it will save ath10k from performance regression. what was tcp "before"? (I'm sorry, such a long thread) >> >>> >>> On Fri, 6 May 2016 11:42:43 +0200 >>> Jesper Dangaard Brouer <bro...@redhat.com> wrote: >>> >>>> Hi Felix, >>>> >>>> This is an important fix for OpenWRT, please read! >>>> >>>> OpenWRT changed the default fq_codel sch->limit from 10240 to 1024, >>>> without also adjusting q->flows_cnt. Eric explains below that you must >>>> also adjust the buckets (q->flows_cnt) for this not to break. (Just >>>> adjust it to 128) >>>> >>>> Problematic OpenWRT commit in question: >>>> http://git.openwrt.org/?p=openwrt.git;a=patch;h=12cd6578084e >>>> 12cd6578084e ("kernel: revert fq_codel quantum override to prevent it >>>> from causing too much cpu load with higher speed (#21326)") >>>> >>>> >>>> I also highly recommend you cherry-pick this very recent commit: >>>> net-next: 9d18562a2278 ("fq_codel: add batch ability to fq_codel_drop()") >>>> https://git.kernel.org/davem/net-next/c/9d18562a227 >>>> >>>> This should fix very high CPU usage in-case fq_codel goes into drop mode. >>>> The problem is that drop mode was considered rare, and implementation >>>> wise it was chosen to be more expensive (to save cycles on normal mode). >>>> Unfortunately is it easy to trigger with an UDP flood. Drop mode is >>>> especially expensive for smaller devices, as it scans a 4K big array, >>>> thus 64 cache misses for small devices! >>>> >>>> The fix is to allow drop-mode to bulk-drop more packets when entering >>>> drop-mode (default 64 bulk drop). That way we don't suddenly >>>> experience a significantly higher processing cost per packet, but >>>> instead can amortize this. >>>> >>>> To Eric, should we recommend OpenWRT to adjust default (max) 64 bulk >>>> drop, given we also recommend bucket size to be 128 ? (thus the amount >>>> of memory to scan is less, but their CPU is also much smaller). >>>> >>>> --Jesper >>>> >>>> >>>> On Thu, 05 May 2016 12:23:27 -0700 Eric Dumazet <eric.duma...@gmail.com> >>>> wrote: >>>> >>>> > On Thu, 2016-05-05 at 19:25 +0300, Roman Yeryomin wrote: >>>> > > On 5 May 2016 at 19:12, Eric Dumazet <eric.duma...@gmail.com> wrote: >>>> > > > On Thu, 2016-05-05 at 17:53 +0300, Roman Yeryomin wrote: >>>> > > > >>>> > > >> >>>> > > >> qdisc fq_codel 0: dev eth0 root refcnt 2 limit 1024p flows 1024 >>>> > > >> quantum 1514 target 5.0ms interval 100.0ms ecn >>>> > > >> Sent 12306 bytes 128 pkt (dropped 0, overlimits 0 requeues 0) >>>> > > >> backlog 0b 0p requeues 0 >>>> > > >> maxpacket 0 drop_overlimit 0 new_flow_count 0 ecn_mark 0 >>>> > > >> new_flows_len 0 old_flows_len 0 >>>> > > > >>>> > > > >>>> > > > Limit of 1024 packets and 1024 flows is not wise I think. >>>> > > > >>>> > > > (If all buckets are in use, each bucket has a virtual queue of 1 >>>> > > > packet, >>>> > > > which is almost the same than having no queue at all) >>>> > > > >>>> > > > I suggest to have at least 8 packets per bucket, to let Codel have a >>>> > > > chance to trigger. >>>> > > > >>>> > > > So you could either reduce number of buckets to 128 (if memory is >>>> > > > tight), or increase limit to 8192. >>>> > > >>>> > > Will try, but what I've posted is default, I didn't change/configure >>>> > > that. >>>> > >>>> > fq_codel has a default of 10240 packets and 1024 buckets. >>>> > >>>> > http://lxr.free-electrons.com/source/net/sched/sch_fq_codel.c#L413 >>>> > >>>> > If someone changed that in the linux variant you use, he probably should >>>> > explain the rationale. >>> >>> -- >>> Best regards, >>> Jesper Dangaard Brouer >>> MSc.CS, Principal Kernel Engineer at Red Hat >>> Author of http://www.iptv-analyzer.org >>> LinkedIn: http://www.linkedin.com/in/brouer -- Dave Täht Let's go make home routers and wifi faster! With better software! http://blog.cerowrt.org