Vybrid ProcessorsのトピックRe: SocketCAN performance problems

SocketCAN performance problems

kef2 — Wed, 19 Aug 2015 04:55:25 GMT

Hello

As everyone CAN'er knows, good old CAN operates at up to 1MHz bit rate clock, one extended ID message is roughly 100 bit times long. That's up to 10k messages per second, which is a piece of cake to handle on 16bit S12 operating at much less than 25MHz bus clock. 10k msgs / sec is also piece of cake for bare metal Vybrid app. But unfortunately it is not a piece of cake for Linux and SocketCAN.

SocketCAN, VF61, 3.13 kernel, no user app working, 5-6 kmsgs / sec on CAN bus. Htop shows ~30% CPU usage... Start one app, which just selects and waits for CAN socket and pulls messages from SocketCAN - CPU usage rises to ~70%... And I would like to have few similar CAN apps operating simultaneously...

Thanks for ideas.

Edward

Re: SocketCAN performance problems

karina_valencia — Mon, 24 Aug 2015 17:05:59 GMT

timesyssupport can you help here?

Re: SocketCAN performance problems

timesyssupport — Thu, 27 Aug 2015 17:38:42 GMT

Hello,

Our testing of CAN has been limited to basic FlexCAN driver functionality in the 3.13 kernel; a loopback on the evaluation board, and between board communication with Vybrid Tower and MX6 based evaluation board. Performance metrics were not captured at this time, but it seems the FlexCAN driver likely needs work to perform well - as evidenced by other instances of the FlexCAN driver on older/current Freescale hardware.

karinavalencia - is there a Freescale engineer who may be more familiar with the inner workings of the CAN support to assist?

Thank you,

Timesys Support

Re: SocketCAN performance problems

karina_valencia — Thu, 27 Aug 2015 17:44:21 GMT

alejandrolozano are you able to help here?

Re: SocketCAN performance problems

kef2 — Mon, 31 Aug 2015 07:14:37 GMT

I tried to compare on-chip FlexCAN driver vs sysWORXX USB<->CAN dongle.

1) CAN bus connected to FlexCAN, ~6 kmessages / sec on the bus, CAN application is not running. CPU load is about 30%. Starting CAN application CPU load ~ doubles.

2) CAN bus connected to sysWORXX USB dongle, ~6 kmessages / sec, CAN application running. CPU load << 10%.

No idea how to fix driver. Source looks good.

Re: SocketCAN performance problems

alejandrolozan1 — Mon, 31 Aug 2015 20:36:51 GMT

Hi,

If you want to increase the performance I would try to use the flexcan driver of MQX with the M4. This in case you need a Real Time feature in your application.

Best Regards,

Alejandro

Re: SocketCAN performance problems

kef2 — Tue, 01 Sep 2015 04:07:02 GMT

Yeah, second MCU or switching to competition MCU also would do. And what to do if VF5's are ordered, no M4 and MQX? Is 6kHz interrupt rate killer for Vybrid Linux? I can't believe that USB is easier to handle with all those layers and etc. Isochronous USB HS still needs 8kHz interrupt rate. Even if interrupt rate is killer, why running read-from-CAN application doubles CPU load? FlexCAN buffers are read already, what's the problem reading buffers from app? Why there's no problem at all doing the same with USB<->CAN dongle?????

Re: SocketCAN performance problems

karina_valencia — Mon, 07 Sep 2015 16:26:28 GMT

alejandrolozano can you continue with the follow up?

Re: SocketCAN performance problems

alejandrolozan1 — Tue, 08 Sep 2015 19:30:04 GMT

Hi,

Let me check if the FlexCAN driver is the problem which I really doubt it. I will see if Rx FIFO is configured, but I wonder if timesyssupport can add more inputs regarding the network and socket layer.

The FlexCAN module should only interrupt when a valid ID frame is received. Do you have the same behavior using candump?

/Alejandro

Re: SocketCAN performance problems

kef2 — Wed, 09 Sep 2015 12:58:29 GMT

I see no bus errors, just few Rx overruns. No user application is running except Htop, no candump, just configured CAN interface and ~6k msgs / sec on the bus.

# ip -det -stat link show can0

2: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UNKNOWN mode DEFAULT group default qlen 10

link/can promiscuity 0

can state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 0

bitrate 1000000 sample-point 0.727

tq 90 prop-seg 3 phase-seg1 4 phase-seg2 3 sjw 1

flexcan: tseg1 4..16 tseg2 2..8 sjw 1..4 brp 1..256 brp-inc 1

clock 66000000

re-started bus-errors arbit-lost error-warn error-pass bus-off

0 0 0 0 0 0

RX: bytes packets errors dropped overrun mcast

2385372 1192686 239 0 239 0

TX: bytes packets errors dropped carrier collsns

0 0 0 0 0 0

CPU[#*************           42.0%]     Tasks: 4, 0 thr; 1 running
Mem[||**                   7/120MB]     Load average: 0.32 0.20 0.09
Swp[                         0/0MB]     Uptime: 00:08:29

PID USER      PRI NI VIRT   RES   SHR S CPU% MEM%   TIME+ Command
1023 root       20   0 2872 1180   984 R 4.6 1.0 0:00.32 htop
    1 root       20   0 2264   672   600 S 0.0 0.5 0:00.68 init
873 root       20   0 2264   448   392 S 0.0 0.4 0:00.01 syslogd
929 root       20   0 2268   696   628 S 0.0 0.6 0:00.34 -/bin/sh

Above is for FlexCAN driver.

sysWORXX I mentioned above is USB<->CAN dongle from Systec. With their dongle and compiled driver CPU load is kind of "have nothing to do".

Thanks.

Re: SocketCAN performance problems

karina_valencia — Mon, 14 Sep 2015 15:21:25 GMT

alejandrolozano please continue with the follow up

Re: SocketCAN performance problems

alejandrolozan1 — Mon, 14 Sep 2015 21:43:06 GMT

The flexcan driver looks ok and it is almost the same as the imx6 family.

I think this is a problem in a different layer and maybe timesyssupport can provide some inputs.

/Alejandro

Re: SocketCAN performance problems

karina_valencia — Mon, 14 Sep 2015 22:00:41 GMT

timesyssupport can you share your comments on this case?

Re: SocketCAN performance problems

timesyssupport — Thu, 17 Sep 2015 17:48:23 GMT

Hello karinavalencia alejandrolozano and kef,

We are looking into this; however, CAN testing was not extensively tested beyond basic driver validation, as previously mentioned. We will follow up after review.

Thank you,

Timesys Support

Re: SocketCAN performance problems

karina_valencia — Mon, 21 Sep 2015 16:15:26 GMT

timesyssupport do you have an estimated due date to have an update?

Re: SocketCAN performance problems

timesyssupport — Mon, 21 Sep 2015 16:51:15 GMT

Hello Karina,

At least a few days; current efforts are concentrated on updating MCC/MQX support in the 3.13 kernel.

Thank you,

Timesys Support

Re: SocketCAN performance problems

karina_valencia — Mon, 28 Sep 2015 17:04:50 GMT

Timesys Support do you have an update?

Re: SocketCAN performance problems

karina_valencia — Mon, 05 Oct 2015 16:20:03 GMT

reminder

Timesys Support do you have an update?

Re: SocketCAN performance problems

timesyssupport — Tue, 06 Oct 2015 18:59:07 GMT

Hello Edward and karinavalencia,

We are not able to reproduce the processor consumption on a Tower VF610 evaluation kit.

We have configured and brought up the FlexCAN device, and see .3% CPU consumption at most in Busybox top; running htop, CPU consumption rises to 2%. But we are not seeing any other processor consumption at idle with just the device enabled and configured. Transmitting over CAN also does not show any changes in CPU consumption.

Are you able to provide a test application case which shows this behavior?

Thank you,

Timesys Support

Re: SocketCAN performance problems

karina_valencia — Tue, 06 Oct 2015 20:58:59 GMT

kef2 can you provide the information requested?