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Date: Sat, 10 Nov 2018 23:19:50 +0100
From: Paweł Staszewski <pstaszewski@...are.pl>
To: Jesper Dangaard Brouer <brouer@...hat.com>
Cc: Saeed Mahameed <saeedm@...lanox.com>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: Kernel 4.19 network performance - forwarding/routing normal users
traffic
W dniu 10.11.2018 o 23:06, Jesper Dangaard Brouer pisze:
> On Sat, 10 Nov 2018 20:56:02 +0100
> Paweł Staszewski <pstaszewski@...are.pl> wrote:
>
>> W dniu 10.11.2018 o 20:49, Paweł Staszewski pisze:
>>>
>>> W dniu 10.11.2018 o 20:34, Jesper Dangaard Brouer pisze:
>>>> On Fri, 9 Nov 2018 23:20:38 +0100 Paweł Staszewski
>>>> <pstaszewski@...are.pl> wrote:
>>>>
>>>>> W dniu 08.11.2018 o 20:12, Paweł Staszewski pisze:
>>>>>> CPU load is lower than for connectx4 - but it looks like bandwidth
>>>>>> limit is the same :)
>>>>>> But also after reaching 60Gbit/60Gbit
>>>>>>
>>>>>> bwm-ng v0.6.1 (probing every 1.000s), press 'h' for help
>>>>>> input: /proc/net/dev type: rate
>>>>>> - iface Rx Tx Total
>>>>>> ===================================================================
>>>>>>
>>>>>>
>>>>>> enp175s0: 45.09 Gb/s 15.09 Gb/s 60.18 Gb/s
>>>>>> enp216s0: 15.14 Gb/s 45.19 Gb/s 60.33 Gb/s
>>>>>> -------------------------------------------------------------------
>>>>>>
>>>>>>
>>>>>> total: 60.45 Gb/s 60.48 Gb/s 120.93 Gb/s
>>>>> Today reached 65/65Gbit/s
>>>>>
>>>>> But starting from 60Gbit/s RX / 60Gbit TX nics start to drop packets
>>>>> (with 50%CPU on all 28cores) - so still there is cpu power to use :).
>>>> This is weird!
>>>>
>>>> How do you see / measure these drops?
>>> Simple icmp test like ping -i 0.1
>>> And im testing by icmp management ip address on vlan that is attacked
>>> to one NIC (the side that is more stressed with RX)
>>> And another icmp test is forward thru this router - host behind it
>>>
>>> Both measurements shows same loss ratio from 0.1 to 0.5% after
>>> reaching ~45Gbit/s RX side - depends how much RX side is pushed drops
>>> vary between 0.1 to 0.5 - even 0.6%:)
>>>
> Okay good to know, you use an external measurement for this. I do
> think packets are getting dropped by the NIC.
>
>>>>> So checked other stats.
>>>>> softnet_stats shows average 1k squeezed per sec:
>>>> Is below output the raw counters? not per sec?
>>>>
>>>> It would be valuable to see the per sec stats instead...
>>>> I use this tool:
>>>> https://github.com/netoptimizer/network-testing/blob/master/bin/softnet_stat.pl
>> CPU total/sec dropped/sec squeezed/sec collision/sec rx_rps/sec flow_limit/sec
>> CPU:00 0 0 0 0 0 0
> [...]
>> CPU:13 0 0 0 0 0 0
>> CPU:14 485538 0 43 0 0 0
>> CPU:15 474794 0 51 0 0 0
>> CPU:16 449322 0 41 0 0 0
>> CPU:17 476420 0 46 0 0 0
>> CPU:18 440436 0 38 0 0 0
>> CPU:19 501499 0 49 0 0 0
>> CPU:20 459468 0 49 0 0 0
>> CPU:21 438928 0 47 0 0 0
>> CPU:22 468983 0 40 0 0 0
>> CPU:23 446253 0 47 0 0 0
>> CPU:24 451909 0 46 0 0 0
>> CPU:25 479373 0 55 0 0 0
>> CPU:26 467848 0 49 0 0 0
>> CPU:27 453153 0 51 0 0 0
>> CPU:28 0 0 0 0 0 0
> [...]
>> CPU:40 0 0 0 0 0 0
>> CPU:41 0 0 0 0 0 0
>> CPU:42 466853 0 43 0 0 0
>> CPU:43 453059 0 54 0 0 0
>> CPU:44 363219 0 34 0 0 0
>> CPU:45 353632 0 38 0 0 0
>> CPU:46 371618 0 40 0 0 0
>> CPU:47 350518 0 46 0 0 0
>> CPU:48 397544 0 40 0 0 0
>> CPU:49 364873 0 38 0 0 0
>> CPU:50 383630 0 38 0 0 0
>> CPU:51 358771 0 39 0 0 0
>> CPU:52 372547 0 38 0 0 0
>> CPU:53 372882 0 36 0 0 0
>> CPU:54 366244 0 43 0 0 0
>> CPU:55 365886 0 39 0 0 0
>>
>> Summed: 11835201 0 1217 0 0 0
>
> Do notice, the per CPU squeeze is not too large.
Yes - but im searching invisible thing now :) something invisible is
slowing down packet processing :)
So trying to find any counter that have something to do with packet
processing.
> The summed 11.8 Mpps is a little high compared to:
>
> Ethtool(enp216s0) stat: 4971677 (4,971,677) <= rx_packets /sec
> Ethtool(enp175s0) stat: 3717148 (3,717,148) <= rx_packets /sec
> Sum: 3717148+4971677 = 8688825 (8,688,825)
Yes i was mentioning this that stats from /net/dev for nics are weird if
u compare them to ethtool - there are big differences for mellanox nic's
Especially with packets/s
For example when i change
- cqe to compress i have more interrupts - same as more packets/s - but
same bw
- change ring settings - like half hour before - changed TX fing from
4096 to 256 and i have less interrupts and less packets but more
bandwidth... weird...
Cause in normal traffic more packets/s need to be more bandwidth - if
average frame is 500-600 if I gain like 1M+pps - then it should mean in
average +5/6Gbit/s more
But it looks like it is more comparable to number of interrupts not
number of packets.
>
> [...]
>>>>> Remember those tests are now on two separate connectx5 connected to
>>>>> two separate pcie x16 gen 3.0
>>>> That is strange... I still suspect some HW NIC issue, can you provide
>>>> ethtool stats info via tool:
>>>>
>>>> https://github.com/netoptimizer/network-testing/blob/master/bin/ethtool_stats.pl
>>>>
>>>> $ ethtool_stats.pl --dev enp175s0 --dev enp216s0
>>>>
>>>> The tool remove zero-stats counters and report per sec stats. It makes
>>>> it easier to spot that is relevant for the given workload.
>>> yes mlnx have just too many counters that are always 0 for my case :)
>>> Will try this also
>>>
>> But still alot of non 0 counters
>> Show adapter(s) (enp175s0 enp216s0) statistics (ONLY that changed!)
>> Ethtool(enp175s0) stat: 8891 ( 8,891) <= ch0_arm /sec
> [...]
>
> I have copied the stats over in another document so I can better looks
> at it... and I've found some interesting stats.
>
> E.g. we can see that the NIC hardware is dropping packets.
>
> RX-drops on enp175s0:
>
> (enp175s0) stat: 4850734036 ( 4,850,734,036) <= rx_bytes /sec
> (enp175s0) stat: 5069043007 ( 5,069,043,007) <= rx_bytes_phy /sec
> -218308971 ( -218,308,971) Dropped bytes /sec
>
> (enp175s0) stat: 139602 ( 139,602) <= rx_discards_phy /sec
>
> (enp175s0) stat: 3717148 ( 3,717,148) <= rx_packets /sec
> (enp175s0) stat: 3862420 ( 3,862,420) <= rx_packets_phy /sec
> -145272 ( -145,272) Dropped packets /sec
>
>
> RX-drops on enp216s0 is less:
>
> (enp216s0) stat: 2592286809 ( 2,592,286,809) <= rx_bytes /sec
> (enp216s0) stat: 2633575771 ( 2,633,575,771) <= rx_bytes_phy /sec
> -41288962 ( -41,288,962) Dropped bytes /sec
>
> (enp216s0) stat: 464 (464) <= rx_discards_phy /sec
>
> (enp216s0) stat: 4971677 ( 4,971,677) <= rx_packets /sec
> (enp216s0) stat: 4975563 ( 4,975,563) <= rx_packets_phy /sec
> -3886 ( -3,886) Dropped packets /sec
>
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