[dpdk-users] scheduler issue

[Alex Kiselev]

On 2020-12-11 23:06, Singh, Jasvinder wrote:
>> On 11 Dec 2020, at 21:29, Alex Kiselev <alex at 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.


>> 
>> 
>>>> >
>>>> >
>>>> >
>>>> >>> 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!