[SOLVED] 100% CPU usage when running more than one JLinkGDBServer process

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  • [SOLVED] 100% CPU usage when running more than one JLinkGDBServer process

    I've been using two or three J-Link (Plus and Pro, doesn't matter) debuggers and when there is only one JLinkGDBServer process running, there is no significant CPU usage increase. However, as soon as I start a second process, the CPU usage on at least two of my CPU cores goes to 100% and stays there until I drop back to only one process.

    I'm running Ubuntu 14.04.1 LTS (x86_64) on 64-bit AMD.

    One other person that I know of sees this as well. I didn't see any way to report bugs on the segger.com website so I sent an email to info@segger.com describing the issue. So far, I haven't received any response.

    Does anyone else see this?

  • Hi,

    Thanks for pointing this out. What version of the J-link software are you using? If you do not use the latest version, can you please check if the issue persist with the latest version (V4.96k), in order exclude issues which might have been already fixed in later versions? If the behavior persists, we will check if we can reproduce this here.
    One other person that I know of sees this as well. I didn't see any way to report bugs on the segger.com website so I sent an email to info@segger.com describing the issue. So far, I haven't received any response.

    In general, you can use https://www.segger.com/support/technical-support/ for all J-Link / Flasher related topics. So far we (the J-Link apartment) did not receive this support request but I am sure it will be forwarded during the day.


    Best regards
    Erik
    Please read the forum rules before posting.

    Keep in mind, this is *not* a support forum.
    Our engineers will try to answer your questions between their projects if possible but this can be delayed by longer periods of time.
    Should you be entitled to support you can contact us via our support system: segger.com/ticket/
    Or you can contact us via e-mail.

  • Thanks Erik.

    Okay, I was on v4.96d but I just installed and tried v4.96k (JLinkARM.dll V4.96k (DLL compiled Feb 20 2015 18:53:52)) and the problem persists.

    Its really easy to reproduce -just start two instances of JLinkGDBServer.

    To be precise, these are the command lines that I use (with serial numbers removed):

    $ JLinkGDBServer -select usb=xxx -port 2331
    $ JLinkGDBServer -select usb=yyy -port 2341

    I can connect to and use GDB with both units simultaneously but the host's CPU usage skyrockets.

    I will try the support email from now on.

    Mark
    --

  • Gah! I just realized I downloaded the 32-bit version of v4.96k. I have now downloaded the 64-bit version and it still has the issue.

    Is there a newer firmware I should be using?



    $ JLinkGDBServer -select usb=[xxx] -port 2331
    SEGGER J-Link GDB Server V4.96k Command Line Version

    JLinkARM.dll V4.96k (DLL compiled Feb 20 2015 18:54:22)

    -----GDB Server start settings-----
    GDBInit file: none
    GDB Server Listening port: 2331
    SWO raw output listening port: 2332
    Terminal I/O port: 2333
    Accept remote connection: yes
    Generate logfile: off
    Verify download: off
    Init regs on start: on
    Silent mode: off
    Single run mode: off
    Target connection timeout: 0 ms
    ------J-Link related settings------
    J-Link Host interface: USB
    J-Link script: none
    J-Link settings file: none
    ------Target related settings------
    Target device: unspecified
    Target interface: JTAG
    Target interface speed: 1000kHz
    Target endian: little

    Connecting to J-Link...
    J-Link is connected.
    Firmware: J-Link Pro V4 compiled Jan 29 2015 11:28:55
    Hardware: V4.00
    S/N: [xxx]
    Feature(s): RDI, FlashBP, FlashDL, JFlash, GDB
    Checking target voltage...
    Target voltage: 1.82 V
    Listening on TCP/IP port 2331
    Connecting to target...
    J-Link found 1 JTAG device, Total IRLen = 4
    JTAG ID: 0x4BA00477 (Cortex-M3)
    Connected to target
    Waiting for GDB connection...

  • Hi Mark,

    Thank you for your report.
    We were able to reproduce the problem here, too, and already found a solution.
    It will probably be included in the next patched release version.

    Although it might not cause problems if you are not using it,
    if you are running multiple instances of GDB Server
    you should consider setting -swoport and -telnetport as well.

    Best regards
    Johannes
    Please read the forum rules before posting.

    Keep in mind, this is *not* a support forum.
    Our engineers will try to answer your questions between their projects if possible but this can be delayed by longer periods of time.
    Should you be entitled to support you can contact us via our support system: segger.com/ticket/
    Or you can contact us via e-mail.

  • Hi Mark,

    Has been fixed in V4.96l, available for download at segger.com/jlink-software.html

    Regards
    Johannes
    Please read the forum rules before posting.

    Keep in mind, this is *not* a support forum.
    Our engineers will try to answer your questions between their projects if possible but this can be delayed by longer periods of time.
    Should you be entitled to support you can contact us via our support system: segger.com/ticket/
    Or you can contact us via e-mail.

  • Thanks for the feedback. Good to hear that the issue is solved now.


    - Erik
    Please read the forum rules before posting.

    Keep in mind, this is *not* a support forum.
    Our engineers will try to answer your questions between their projects if possible but this can be delayed by longer periods of time.
    Should you be entitled to support you can contact us via our support system: segger.com/ticket/
    Or you can contact us via e-mail.