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RT-AC86U 384.14_2 - High cpu

Discussion in 'Asuswrt-Merlin' started by Patrick9876, Jan 26, 2020.

  1. Patrick9876

    Patrick9876 Occasional Visitor

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    Pacific Northwest, USA
    My AC86U is currently running around 100%. The actually core use switches around but the total stays around 100-102%. I saw this happen once before and rebooted. That's probably what I will do now, but what kind of diagnosis should I do in the future?

    BTW, after rebooting the cpu usage is peaking around 5%. In the past I've seen it in the 20s.
     
    Last edited: Jan 26, 2020
  2. ColinTaylor

    ColinTaylor Part of the Furniture

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    Have you already read through the existing threads in this forum about high CPU usage? Did any of those sound similar?
     
  3. dave14305

    dave14305 Part of the Furniture

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    Login with SSH and run this command when you see CPU maxed out:
    Code:
    top -bn 1 | head -24
    This should show the top 20 processes using CPU. Run it a few times and post the results that seem the most representative from one run to the next.
     
  4. Patrick9876

    Patrick9876 Occasional Visitor

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    First, embarrassment. I had searched with my router model and found nothing that matched well.

    So I just searched "snbforums high cpu" and found an overwhelming number of hits. Now my embarrassment has turned to anger.

    Several responses suggested turning the router off, keeping it off for a while, and turning it back on. While not helping in diagnosis, that works for my problem. I already knew that worked; I've done it twice now. But I was looking for something a bit less disruptive.

    Some were appropriate for high cpu following firmware upgrade and, if I understood correctly, involved resetting to factory settings. Well, I had done that both before and after upgrading from the out-of-the-box ASUS firmware to Merlin 384.14_2 about 2 weeks ago. (If a procedure that clears all user settings is considered an appropriate procedure by ASUS for a consumer grade product then I think I have the wrong brand of hardware.) But I've made no such changes for 2 weeks. I've made lots of config changes - turning on VPN support, turning on DDNS support, etc., but now firmware upgrades.

    Some suggested clearing nvram as a solution to high cpu. If that is equivalent to resetting to factory settings I've already expressed my opinion of that. I'll continue powering the router down for a few minutes instead. That, at least causes a lot less downtime than needing to reconfigure the router.

    Since I'm not having the problem at the moment, performing this is obviously not showing much useful ... except to show me what normal activity looks like. But I'll save this command and issue it if/when I'm hit with the high cpu condition again and see what it shows.
     
  5. Patrick9876

    Patrick9876 Occasional Visitor

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    It finally happened again.

    Code:
      PID  PPID USER     STAT   VSZ %VSZ CPU %CPU COMMAND
    31810     1 admin_rt R     3020  0.6   1 47.7 /usr/sbin/acsd
    It looks like acsd is the culprit, but that doesn't tell me anything. I have no idea how to kill it or what would happen if I did kill it.
     
  6. DarkKnight75

    DarkKnight75 Regular Contributor

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    I had a ton of 2.4 and 5ghz drops on 384.14 and 384.14.2 I finally reverted back to 384.12 and all is good. You may want to try that version.
     
  7. L&LD

    L&LD Part of the Furniture

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    Or, 384.15_0 may help? :)
     
  8. anonimo

    anonimo New Around Here

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    ACSD is used to scan and select low-interference channels, so if SMART-connect is on and/or auto-channel is selected then setting a fixed channel for each frequency band may alleviate the issue (a cell phone Wi-Fi Analyzer app can help identify the least congested channel). A client, such as a new phone (or older smart-tv), is a more likely culprit than a remote attack.

    I too recommend going to 384.15, but this would be a quick test on your current firmware before making the jump.
     
  9. Patrick9876

    Patrick9876 Occasional Visitor

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    Location:
    Pacific Northwest, USA
    I don't use SMART-connect, but I do have auto-channel selected. I'll set fixed channels.

    We have a couple old (not very) smart-tvs. I'll see if they have wireless support that can be disabled - we don't use it.