-----Original Message-----
From: Alex Kiselev <[email protected]>
Sent: Monday, December 7, 2020 4:50 PM
To: Singh, Jasvinder <[email protected]>
Cc: [email protected]; Dumitrescu, Cristian
<[email protected]>;
Dharmappa, Savinay <[email protected]>
Subject: Re: [dpdk-users] scheduler issue
On 2020-12-07 12:32, Singh, Jasvinder wrote:
>> -----Original Message-----
>> From: Alex Kiselev <[email protected]>
>> Sent: Monday, December 7, 2020 10:46 AM
>> To: Singh, Jasvinder <[email protected]>
>> Cc: [email protected]; Dumitrescu, Cristian
>> <[email protected]>; Dharmappa, Savinay
>> <[email protected]>
>> Subject: Re: [dpdk-users] scheduler issue
>>
>> On 2020-12-07 11:00, Singh, Jasvinder wrote:
>> >> -----Original Message-----
>> >> From: users <[email protected]> On Behalf Of Alex Kiselev
>> >> Sent: Friday, November 27, 2020 12:12 PM
>> >> To: [email protected]
>> >> Cc: Dumitrescu, Cristian <[email protected]>
>> >> Subject: Re: [dpdk-users] scheduler issue
>> >>
>> >> On 2020-11-25 16:04, Alex Kiselev wrote:
>> >> > On 2020-11-24 16:34, Alex Kiselev wrote:
>> >> >> Hello,
>> >> >>
>> >> >> I am facing a problem with the scheduler library DPDK 18.11.10
>> >> >> with default scheduler settings (RED is off).
>> >> >> It seems like some of the pipes (last time it was 4 out of 600
>> >> >> pipes) start incorrectly dropping most of the traffic after a
>> >> >> couple of days of successful work.
>> >> >>
>> >> >> So far I've checked that there are no mbuf leaks or any other
>> >> >> errors in my code and I am sure that traffic enters problematic
pipes.
>> >> >> Also switching a traffic in the runtime to pipes of another
>> >> >> port restores the traffic flow.
>> >> >>
>> >> >> Ho do I approach debugging this issue?
>> >> >>
>> >> >> I've added using rte_sched_queue_read_stats(), but it doesn't
>> >> >> give me counters that accumulate values (packet drops for
>> >> >> example), it gives me some kind of current values and after a
>> >> >> couple of seconds those values are reset to zero, so I can say
nothing based on that API.
>> >> >>
>> >> >> I would appreciate any ideas and help.
>> >> >> Thanks.
>> >> >
>> >> > Problematic pipes had very low bandwidth limit (1 Mbit/s) and
>> >> > also there is an oversubscription configuration event at subport
>> >> > 0 of port
>> >> > 13 to which those pipes belongs and
>> >> CONFIG_RTE_SCHED_SUBPORT_TC_OV is
>> >> > disabled.
>> >> >
>> >> > Could a congestion at that subport be the reason of the problem?
>> >> >
>> >> > How much overhead and performance degradation will add enabling
>> >> > CONFIG_RTE_SCHED_SUBPORT_TC_OV feature?
>> >> >
>> >> > Configuration:
>> >> >
>> >> > #
>> >> > # QoS Scheduler Profiles
>> >> > #
>> >> > hqos add profile 1 rate 8 K size 1000000 tc period 40
>> >> > hqos add profile 2 rate 400 K size 1000000 tc period 40
>> >> > hqos add profile 3 rate 600 K size 1000000 tc period 40
>> >> > hqos add profile 4 rate 800 K size 1000000 tc period 40
>> >> > hqos add profile 5 rate 1 M size 1000000 tc period 40
>> >> > hqos add profile 6 rate 1500 K size 1000000 tc period 40
>> >> > hqos add profile 7 rate 2 M size 1000000 tc period 40
>> >> > hqos add profile 8 rate 3 M size 1000000 tc period 40
>> >> > hqos add profile 9 rate 4 M size 1000000 tc period 40
>> >> > hqos add profile 10 rate 5 M size 1000000 tc period 40
>> >> > hqos add profile 11 rate 6 M size 1000000 tc period 40
>> >> > hqos add profile 12 rate 8 M size 1000000 tc period 40
>> >> > hqos add profile 13 rate 10 M size 1000000 tc period 40
>> >> > hqos add profile 14 rate 12 M size 1000000 tc period 40
>> >> > hqos add profile 15 rate 15 M size 1000000 tc period 40
>> >> > hqos add profile 16 rate 16 M size 1000000 tc period 40
>> >> > hqos add profile 17 rate 20 M size 1000000 tc period 40
>> >> > hqos add profile 18 rate 30 M size 1000000 tc period 40
>> >> > hqos add profile 19 rate 32 M size 1000000 tc period 40
>> >> > hqos add profile 20 rate 40 M size 1000000 tc period 40
>> >> > hqos add profile 21 rate 50 M size 1000000 tc period 40
>> >> > hqos add profile 22 rate 60 M size 1000000 tc period 40
>> >> > hqos add profile 23 rate 100 M size 1000000 tc period 40
>> >> > hqos add profile 24 rate 25 M size 1000000 tc period 40
>> >> > hqos add profile 25 rate 50 M size 1000000 tc period 40
>> >> >
>> >> > #
>> >> > # Port 13
>> >> > #
>> >> > hqos add port 13 rate 40 G mtu 1522 frame overhead 24 queue
>> >> > sizes
>> >> > 64
>> >> > 64 64 64
>> >> > hqos add port 13 subport 0 rate 1500 M size 1000000 tc period 10
>> >> > hqos add port 13 subport 0 pipes 3000 profile 2
>> >> > hqos add port 13 subport 0 pipes 3000 profile 5
>> >> > hqos add port 13 subport 0 pipes 3000 profile 6
>> >> > hqos add port 13 subport 0 pipes 3000 profile 7
>> >> > hqos add port 13 subport 0 pipes 3000 profile 9
>> >> > hqos add port 13 subport 0 pipes 3000 profile 11
>> >> > hqos set port 13 lcore 5
>> >>
>> >> I've enabled TC_OV feature and redirected most of the traffic to TC3.
>> >> But the issue still exists.
>> >>
>> >> Below is queue statistics of one of problematic pipes.
>> >> Almost all of the traffic entering the pipe is dropped.
>> >>
>> >> And the pipe is also configured with the 1Mbit/s profile.
>> >> So, the issue is only with very low bandwidth pipe profiles.
>> >>
>> >> And this time there was no congestion on the subport.
>> >>
>> >>
>> >> Egress qdisc
>> >> dir 0
>> >> rate 1M
>> >> port 6, subport 0, pipe_id 138, profile_id 5
>> >> tc 0, queue 0: bytes 752, bytes dropped 0, pkts 8, pkts dropped 0
>> >> tc 0, queue 1: bytes 0, bytes dropped 0, pkts 0, pkts dropped 0
>> >> tc 0, queue 2: bytes 0, bytes dropped 0, pkts 0, pkts dropped 0
>> >> tc 0, queue 3: bytes 0, bytes dropped 0, pkts 0, pkts dropped 0
>> >> tc 1, queue 0: bytes 0, bytes dropped 0, pkts 0, pkts dropped 0
>> >> tc 1, queue 1: bytes 0, bytes dropped 0, pkts 0, pkts dropped 0
>> >> tc 1, queue 2: bytes 0, bytes dropped 0, pkts 0, pkts dropped 0
>> >> tc 1, queue 3: bytes 0, bytes dropped 0, pkts 0, pkts dropped 0
>> >> tc 2, queue 0: bytes 0, bytes dropped 0, pkts 0, pkts dropped 0
>> >> tc 2, queue 1: bytes 0, bytes dropped 0, pkts 0, pkts dropped 0
>> >> tc 2, queue 2: bytes 0, bytes dropped 0, pkts 0, pkts dropped 0
>> >> tc 2, queue 3: bytes 0, bytes dropped 0, pkts 0, pkts dropped 0
>> >> tc 3, queue 0: bytes 56669, bytes dropped 360242, pkts 150,
>> >> pkts dropped
>> >> 3749
>> >> tc 3, queue 1: bytes 63005, bytes dropped 648782, pkts 150,
>> >> pkts dropped
>> >> 3164
>> >> tc 3, queue 2: bytes 9984, bytes dropped 49704, pkts 128, pkts
>> >> dropped
>> >> 636
>> >> tc 3, queue 3: bytes 15436, bytes dropped 107198, pkts 130,
>> >> pkts dropped
>> >> 354
>> >
>> >
>> > Hi Alex,
>> >
>> > Can you try newer version of the library, say dpdk 20.11?
>>
>> Right now no, since switching to another DPDK will take a lot of time
>> because I am using a lot of custom patches.
>>
>> I've tried to simply copy the entire rte_sched lib from DPDK 19 to
>> DPDK 18.
>> And I was able to successful back port and resolve all dependency
>> issues, but it also will take some time to test this approach.
>>
>>
>> > Are you
>> > using dpdk qos sample app or your own app?
>>
>> My own app.
>>
>> >> What are the packets size?
>>
>> Application is used as BRAS/BNG server, so it's used to provide
>> internet access to residential customers. Therefore packet sizes are
>> typical to the internet and vary from 64 to 1500 bytes. Most of the
>> packets are around
>> 1000 bytes.
>>
>> >
>> > Couple of other things for clarification- 1. At what rate you are
>> > injecting the traffic to low bandwidth pipes?
>>
>> Well, the rate vary also, there could be congestion on some pipes at
>> some date time.
>>
>> But the problem is that once the problem occurs at a pipe or at some
>> queues inside the pipe, the pipe stops transmitting even when
>> incoming traffic rate is much lower than the pipe's rate.
>>
>> > 2. How is traffic distributed among pipes and their traffic class?
>>
>> I am using IPv4 TOS field to choose the TC and there is a tos2tc map.
>> Most of my traffic has 0 tos value which is mapped to TC3 inside my
>> app.
>>
>> Recently I've switched to a tos2map which maps all traffic to TC3 to
>> see if it solves the problem.
>>
>> Packet distribution to queues is done using the formula (ipv4.src +
>> ipv4.dst) & 3
>>
>> > 3. Can you try putting your own counters on those pipes queues
>> > which periodically show the #packets in the queues to understand
>> > the dynamics?
>>
>> I will try.
>>
>> P.S.
>>
>> Recently I've got another problem with scheduler.
>>
>> After enabling the TC_OV feature one of the ports stops transmitting.
>> All port's pipes were affected.
>> Port had only one support, and there were only pipes with 1 Mbit/s
>> profile.
>> The problem was solved by adding a 10Mit/s profile to that port. Only
>> after that port's pipes started to transmit.
>> I guess it has something to do with calculating tc_ov_wm as it
>> depends on the maximum pipe rate.
>>
>> I am gonna make a test lab and a test build to reproduce this.
I've made some tests and was able to reproduce the port configuration
issue
using a test build of my app.
Tests showed that TC_OV feature works not correctly in DPDK 18.11, but
there are workarounds.
I still can't reproduce my main problem which is random pipes stop
transmitting.
Here are details:
All tests use the same test traffic generator that produce
10 traffic flows entering 10 different pipes of port 1 subport 0.
Only queue 0 of each pipe is used.
TX rate is 800 kbit/s. packet size is 800 byte.
Pipes rate are 1 Mbit/s. Subport 0 rate is 500 Mbit/s.
###
### test 1
###
Traffic generator is configured to use TC3.
Configuration:
hqos add profile 27 rate 1 M size 1000000 tc period 40
hqos add profile 23 rate 100 M size 1000000 tc period 40
# qos test port
hqos add port 1 rate 10 G mtu 1522 frame overhead 24 queue sizes 64
64
64 64
hqos add port 1 subport 0 rate 500 M size 1000000 tc period 10
hqos add port 1 subport 0 pipes 2000 profile 27
hqos set port 1 lcore 3
Results:
h5 ~ # rcli sh qos rcv
rcv 0: rx rate 641280, nb pkts 501, ind 1 rcv 1: rx rate 641280, nb
pkts 501, ind
1 rcv 2: rx rate 641280, nb pkts 501, ind 1 rcv 3: rx rate 641280, nb
pkts 501,
ind 1 rcv 4: rx rate 641280, nb pkts 501, ind 1 rcv 5: rx rate 641280,
nb pkts
501, ind 1 rcv 6: rx rate 641280, nb pkts 501, ind 1 rcv 7: rx rate
641280, nb
pkts 501, ind 1 rcv 8: rx rate 641280, nb pkts 501, ind 1 rcv 9: rx
rate 641280,
nb pkts 501, ind 1
! BUG
! RX rate is lower then expected 800000 bit/s despite that there is no
congestion neither at subport nor at pipes levels.
