On 2020-12-12 01:20, Singh, Jasvinder wrote:
On 11 Dec 2020, at 23:37, Alex Kiselev <[email protected]> wrote:
On 2020-12-11 23:55, Singh, Jasvinder wrote:
On 11 Dec 2020, at 22:27, Alex Kiselev <[email protected]> wrote:
On 2020-12-11 23:06, Singh, Jasvinder wrote:
On 11 Dec 2020, at 21:29, Alex Kiselev <[email protected]> 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!
