From: Alex Kiselev <alex@therouter.net>
To: "Singh, Jasvinder" <jasvinder.singh@intel.com>
Cc: users@dpdk.org, "Dumitrescu,
Cristian" <cristian.dumitrescu@intel.com>,
"Dharmappa, Savinay" <savinay.dharmappa@intel.com>
Subject: Re: [dpdk-users] scheduler issue
Date: Sat, 12 Dec 2020 01:45:23 +0100 [thread overview]
Message-ID: <4ed02c4280efcfe2bf9e6c51803f807b@therouter.net> (raw)
In-Reply-To: <85944DCD-F0D5-4F64-9E8C-68D1428491B8@intel.com>
On 2020-12-12 01:20, Singh, Jasvinder wrote:
>> On 11 Dec 2020, at 23:37, Alex Kiselev <alex@therouter.net> wrote:
>
>> On 2020-12-11 23:55, Singh, Jasvinder wrote:
>> On 11 Dec 2020, at 22:27, Alex Kiselev <alex@therouter.net> wrote:
>
>>> On 2020-12-11 23:06, Singh, Jasvinder wrote:
>
>> On 11 Dec 2020, at 21:29, Alex Kiselev <alex@therouter.net> wrote:
>
>> On 2020-12-08 14:24, Singh, Jasvinder wrote:
>
>> <snip>
>
>>> [JS] now, returning to 1 mbps pipes situation, try reducing tc
>> period
>
>>> first at subport and then at pipe level, if that help in getting
>> even
>
>>> traffic across low bandwidth pipes.
>
>> reducing subport tc from 10 to 5 period also solved the problem
>> with 1
>
>> Mbit/s pipes.
>
>> so, my second problem has been solved,
>
>> but the first one with some of low bandwidth pipes stop
>> transmitting still
>
>> remains.
>
>> I see, try removing "pkt_len <= pipe_tc_ov_credits" condition in
>> the
>
>> grinder_credits_check() code for oversubscription case, instead use
>
>> this pkt_len <= pipe_tc_credits + pipe_tc_ov_credits;
>
>> if I do what you suggest, I will get this code
>
>> enough_credits = (pkt_len <= subport_tb_credits) &&
>
>> (pkt_len <= subport_tc_credits) &&
>
>> (pkt_len <= pipe_tb_credits) &&
>
>> (pkt_len <= pipe_tc_credits) &&
>
>> (pkt_len <= pipe_tc_credits + pipe_tc_ov_credits);
>
>> And this doesn't make sense since if condition pkt_len <=
>> pipe_tc_credits is true
>
>> then condition (pkt_len <= pipe_tc_credits + pipe_tc_ov_credits) is
>> also always true.
>
>> [JS] my suggestion is to remove“pkt_len <= pipe_tc_credits“,
>> “ pkt_len
>
>> <= pipe_tc_ov_credits”and use only “pkt_len <= pipe_tc_credits
>> +
>
>> pipe_tc_ov_credits“
>
>> While keeping tc_ov flag on.
>
>> Your suggestion just turns off TC_OV feature.
>
>>> I don't see your point.
>
>>> This new suggestion will also effectively turn off the TC_OV
>>> feature since
>
>>> the only effect of enabling TC_OV is adding additional condition
>
>>> pkt_len <= pipe_tc_ov_credits
>
>>> which doesn't allow a pipe to spend more resources than it should.
>
>>> And in the case of support congestion a pipe should spent less
>>> than %100 of pipe's maximum rate.
>
>>> And you suggest to allow pipe to spend 100% of it's rate plus some
>>> extra.
>
>>> I guess effect of this would even more unfair support's bandwidth
>>> distibution.
>
>>> Btw, a pipe might stop transmitting even when there is no
>>> congestion at a subport.
>
>> Although I didn’t try this solution but the idea here is - in a
>
>> particular round, of pkt_len is less than pipe_tc_credits( which is
>> a
>
>> constant value each time) but greater than pipe_tc_ov_credits, then
>> it
>
>> might hit the situation when no packet will be scheduled from the
>> pipe
>
>> even though there are fixed credits greater than packet size is
>
>> available.
>
> But that is a perfectly normal situation and that's exactly the idea
> behind TC_OV.
> It means a pipe should wait for the next subport->tc_ov_period_id
> when pipe_tc_ov_credits will be reset to a new value
>
> But here it’s not guaranteed that new value of pipe_tc_ov_credits
> will be sufficient for low bandwidth pipe to send their packets as
> each time pipe_tc_ov_credits is freshly computed.
>
>> pipe->tc_ov_credits = subport->tc_ov_wm * params->tc_ov_weight;
>>
>> which allows the pipe to continue transmitting.
>
> No that won’t happen if new tc_ov_credits value is again less than
> pkt_len and will hit deadlock.
new tc_ov_credits can't not be less than subport->tc_ov_wm_min,
and tc_ov_wm_min is equal to port->mtu.
all my scheduler ports configured with mtu 1522. etherdev ports also
uses
the same mtu, therefore there should be no packets bigger that 1522.
Maybe I should increase port's MTU? to 1540?
>
>> And it could not cause a permanent pipe stop which is what I am
>> facing.
>
>>> In fairness, pipe should send the as much as packets which
>>
>>> consumes pipe_tc_credits, regardless of extra pipe_tc_ov_credits
>>> which
>>
>>> is extra on top of pipe_tc_credits.
>>
>> I think it's quite the opposite. That's why after I reduced the
>> support tc_period
>> I got much more fairness. Since reducing subport tc_period also
>> reduce the tc_ov_wm_max value.
>> s->tc_ov_wm_max = rte_sched_time_ms_to_bytes(params->tc_period,
>> port->pipe_tc3_rate_max)
>> as a result a pipe transmits less bytes in one round. so pipe
>> rotation inside a grinder
>> happens much more often and a pipe can't monopolise resources.
>>
>> in other sos implementation this is called "quantum".
>
> Yes, so reducing tc period makes the case when all pipes ( high n low
> bandwidth) gets lower values of tc_ov_credits values which allow
> lesser transmission from higher bw pipes and leave bandwidth for low
> bw pipes. So, here is the thing- Either tune tc period to a value
> which prevent high bw pipe hogging most of bw or makes changes in the
> code, where oversubscription add extra credits on top of guaranteed.
>
> One question, don’t your low bw pipes have higher priority traffic
> tc0, tc1, tc2 . Packets from those tc must be going out. Isn’t this
> the case ?
well, it would be the case after I find out
what's going on. Right now I am using a tos2tc map configured
in such a way that all ipv4 packets with any TOS values
goes into TC3.
>
>>>
>
>>>
>
>>>
>
>>>>> rcv 0 rx rate 7324160 nb pkts 5722
>
>>>>> rcv 1 rx rate 7281920 nb pkts 5689
>
>>>>> rcv 2 rx rate 7226880 nb pkts 5646
>
>>>>> rcv 3 rx rate 7124480 nb pkts 5566
>
>>>>> rcv 4 rx rate 7324160 nb pkts 5722
>
>>>>> rcv 5 rx rate 7271680 nb pkts 5681
>
>>>>> rcv 6 rx rate 7188480 nb pkts 5616
>
>>>>> rcv 7 rx rate 7150080 nb pkts 5586
>
>>>>> rcv 8 rx rate 7328000 nb pkts 5725
>
>>>>> rcv 9 rx rate 7249920 nb pkts 5664
>
>>>>> rcv 10 rx rate 7188480 nb pkts 5616 rcv 11 rx rate 7179520 nb
>> pkts
>
>>>>> 5609 rcv 12 rx rate 7324160 nb pkts 5722 rcv 13 rx rate
>> 7208960 nb
>
>>>>> pkts 5632 rcv 14 rx rate 7152640 nb pkts 5588 rcv 15 rx rate
>
>>>>> 7127040 nb pkts 5568 rcv 16 rx rate 7303680 nb pkts 5706 ....
>
>>>>> rcv 587 rx rate 2406400 nb pkts 1880 rcv 588 rx rate 2406400 nb
>> pkts
>
>>>>> 1880 rcv 589 rx rate 2406400 nb pkts 1880 rcv 590 rx rate
>> 2406400 nb
>
>>>>> pkts 1880 rcv 591 rx rate 2406400 nb pkts 1880 rcv 592 rx rate
>
>>>>> 2398720 nb pkts 1874 rcv 593 rx rate 2400000 nb pkts 1875 rcv
>> 594 rx
>
>>>>> rate 2400000 nb pkts 1875 rcv 595 rx rate 2400000 nb pkts 1875
>> rcv
>
>>>>> 596 rx rate 2401280 nb pkts 1876 rcv 597 rx rate 2401280 nb
>> pkts
>
>>>>> 1876 rcv 598 rx rate 2401280 nb pkts 1876 rcv 599 rx rate
>> 2402560 nb
>
>>>>> pkts 1877 rx rate sum 3156416000
>
>>>>
>
>>>>
>
>>>>
>
>>>>>>> ... despite that there is _NO_ congestion...
>
>>>>>>> congestion at the subport or pipe.
>
>>>>>>>> And the subport !! doesn't use about 42 mbit/s of available
>
>>>>>>>> bandwidth.
>
>>>>>>>> The only difference is those test configurations is TC of
>
>>>>>>>> generated traffic.
>
>>>>>>>> Test 1 uses TC 1 while test 2 uses TC 3 (which is use TC_OV
>
>>>>>>>> function).
>
>>>>>>>> So, enabling TC_OV changes the results dramatically.
>
>>>>>>>> ##
>
>>>>>>>> ## test1
>
>>>>>>>> ##
>
>>>>>>>> hqos add profile 7 rate 2 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 300 M size 1000000 tc period
>> 10
>
>>>>>>>> hqos add port 1 subport 0 pipes 2000 profile 7 hqos add port
>> 1
>
>>>>>>>> subport 0 pipes 200 profile 23 hqos set port 1 lcore 3 port
>> 1
>
>>>>>>>> subport rate 300 M number of tx flows 300 generator tx rate
>> 1M TC
>
>>>>>>>> 1 ...
>
>>>>>>>> rcv 284 rx rate 995840 nb pkts 778 rcv 285 rx rate 995840
>> nb
>
>>>>>>>> pkts 778 rcv 286 rx rate 995840 nb pkts 778 rcv 287 rx rate
>
>>>>>>>> 995840 nb pkts 778 rcv 288 rx rate 995840 nb pkts 778 rcv
>> 289
>
>>>>>>>> rx rate 995840 nb pkts 778 rcv 290 rx rate 995840 nb pkts
>> 778
>
>>>>>>>> rcv 291 rx rate 995840 nb pkts 778 rcv 292 rx rate 995840
>> nb
>
>>>>>>>> pkts 778 rcv 293 rx rate 995840 nb pkts 778 rcv 294 rx rate
>
>>>>>>>> 995840 nb pkts 778 ...
>
>>>>>>>> sum pipe's rx rate is 298 494 720 OK.
>
>>>>>>>> The subport rate is equally distributed to 300 pipes.
>
>>>>>>>> ##
>
>>>>>>>> ## test 2
>
>>>>>>>> ##
>
>>>>>>>> hqos add profile 7 rate 2 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 300 M size 1000000 tc period
>> 10
>
>>>>>>>> hqos add port 1 subport 0 pipes 2000 profile 7 hqos add port
>> 1
>
>>>>>>>> subport 0 pipes 200 profile 23 hqos set port 1 lcore 3 port
>> 1
>
>>>>>>>> subport rate 300 M number of tx flows 300 generator tx rate
>> 1M TC
>
>>>>>>>> 3
>
>>>>>>>> h5 ~ # rcli sh qos rcv
>
>>>>>>>> rcv 0 rx rate 875520 nb pkts 684
>
>>>>>>>> rcv 1 rx rate 856320 nb pkts 669
>
>>>>>>>> rcv 2 rx rate 849920 nb pkts 664
>
>>>>>>>> rcv 3 rx rate 853760 nb pkts 667
>
>>>>>>>> rcv 4 rx rate 867840 nb pkts 678
>
>>>>>>>> rcv 5 rx rate 844800 nb pkts 660
>
>>>>>>>> rcv 6 rx rate 852480 nb pkts 666
>
>>>>>>>> rcv 7 rx rate 855040 nb pkts 668
>
>>>>>>>> rcv 8 rx rate 865280 nb pkts 676
>
>>>>>>>> rcv 9 rx rate 846080 nb pkts 661
>
>>>>>>>> rcv 10 rx rate 858880 nb pkts 671 rcv 11 rx rate 870400
>> nb
>
>>>>>>>> pkts 680 rcv 12 rx rate 864000 nb pkts 675 rcv 13 rx rate
>
>>>>>>>> 852480 nb pkts 666 rcv 14 rx rate 855040 nb pkts 668 rcv
>> 15
>
>>>>>>>> rx rate 857600 nb pkts 670 rcv 16 rx rate 864000 nb pkts
>> 675
>
>>>>>>>> rcv 17 rx rate 866560 nb pkts 677 rcv 18 rx rate 865280
>> nb
>
>>>>>>>> pkts 676 rcv 19 rx rate 858880 nb pkts 671 rcv 20 rx rate
>
>>>>>>>> 856320 nb pkts 669 rcv 21 rx rate 864000 nb pkts 675 rcv
>> 22
>
>>>>>>>> rx rate 869120 nb pkts 679 rcv 23 rx rate 856320 nb pkts
>> 669
>
>>>>>>>> rcv 24 rx rate 862720 nb pkts 674 rcv 25 rx rate 865280
>> nb
>
>>>>>>>> pkts 676 rcv 26 rx rate 867840 nb pkts 678 rcv 27 rx rate
>
>>>>>>>> 870400 nb pkts 680 rcv 28 rx rate 860160 nb pkts 672 rcv
>> 29
>
>>>>>>>> rx rate 870400 nb pkts 680 rcv 30 rx rate 869120 nb pkts
>> 679
>
>>>>>>>> rcv 31 rx rate 870400 nb pkts 680 rcv 32 rx rate 858880
>> nb
>
>>>>>>>> pkts 671 rcv 33 rx rate 858880 nb pkts 671 rcv 34 rx rate
>
>>>>>>>> 852480 nb pkts 666 rcv 35 rx rate 874240 nb pkts 683 rcv
>> 36
>
>>>>>>>> rx rate 855040 nb pkts 668 rcv 37 rx rate 853760 nb pkts
>> 667
>
>>>>>>>> rcv 38 rx rate 869120 nb pkts 679 rcv 39 rx rate 885760
>> nb
>
>>>>>>>> pkts 692 rcv 40 rx rate 861440 nb pkts 673 rcv 41 rx rate
>
>>>>>>>> 852480 nb pkts 666 rcv 42 rx rate 871680 nb pkts 681 ...
>
>>>>>>>> ...
>
>>>>>>>> rcv 288 rx rate 766720 nb pkts 599 rcv 289 rx rate 766720
>> nb
>
>>>>>>>> pkts 599 rcv 290 rx rate 766720 nb pkts 599 rcv 291 rx rate
>
>>>>>>>> 766720 nb pkts 599 rcv 292 rx rate 762880 nb pkts 596 rcv
>> 293
>
>>>>>>>> rx rate 762880 nb pkts 596 rcv 294 rx rate 762880 nb pkts
>> 596
>
>>>>>>>> rcv 295 rx rate 760320 nb pkts 594 rcv 296 rx rate 604160
>> nb
>
>>>>>>>> pkts 472 rcv 297 rx rate 604160 nb pkts 472 rcv 298 rx rate
>
>>>>>>>> 604160 nb pkts 472 rcv 299 rx rate 604160 nb pkts 472 rx
>> rate
>
>>>>>>>> sum 258839040 FAILED.
>
>>>>>>>> The subport rate is distributed NOT equally between 300
>> pipes.
>
>>>>>>>> Some subport bandwith (about 42) is not being used!
next prev parent reply other threads:[~2020-12-12 0:45 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-24 13:34 Alex Kiselev
2020-11-25 15:04 ` Alex Kiselev
2020-11-27 12:11 ` Alex Kiselev
2020-12-07 10:00 ` Singh, Jasvinder
2020-12-07 10:46 ` Alex Kiselev
2020-12-07 11:32 ` Singh, Jasvinder
2020-12-07 12:29 ` Alex Kiselev
2020-12-07 16:49 ` Alex Kiselev
2020-12-07 17:31 ` Singh, Jasvinder
2020-12-07 17:45 ` Alex Kiselev
[not found] ` <49019BC8-DDA6-4B39-B395-2A68E91AB424@intel.com>
[not found] ` <226b13286c876e69ad40a65858131b66@therouter.net>
[not found] ` <4536a02973015dc8049834635f145a19@therouter.net>
[not found] ` <f9a27b6493ae1e1e2850a3b459ab9d33@therouter.net>
[not found] ` <B8241A33-0927-4411-A340-9DD0BEE07968@intel.com>
[not found] ` <e6a0429dc4a1a33861a066e3401e85b6@therouter.net>
2020-12-07 22:16 ` Alex Kiselev
2020-12-07 22:32 ` Singh, Jasvinder
2020-12-08 10:52 ` Alex Kiselev
2020-12-08 13:24 ` Singh, Jasvinder
2020-12-09 13:41 ` Alex Kiselev
2020-12-10 10:29 ` Singh, Jasvinder
2020-12-11 21:29 ` Alex Kiselev
2020-12-11 22:06 ` Singh, Jasvinder
2020-12-11 22:27 ` Alex Kiselev
2020-12-11 22:36 ` Alex Kiselev
2020-12-11 22:55 ` Singh, Jasvinder
2020-12-11 23:36 ` Alex Kiselev
2020-12-12 0:20 ` Singh, Jasvinder
2020-12-12 0:45 ` Alex Kiselev [this message]
2020-12-12 0:54 ` Alex Kiselev
2020-12-12 1:45 ` Alex Kiselev
2020-12-12 10:22 ` Singh, Jasvinder
2020-12-12 10:46 ` Alex Kiselev
2020-12-12 17:19 ` Alex Kiselev
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