Strange new SNMP bug on 2.4 upgrade (huge CPU usage)



  • I just upgraded to 2.4 from the latest 2.3.x. I noticed the processor was getting swamped at 60% usage or higher, and upon looking further I find it's all SNMPD. On 2.3.x snmpd took about 1%, with the same config. This is with nothing polling it.

    Here's where it gets strange - if I go into snmp settings, and uncheck "host resources", snmpd restarts and goes back to using less than 1% CPU usage. Fixes it across reboots, etc. Re-checking host resources brings back the 50%+ CPU usage every time.

    I've upgraded 3 completely seperate boxes. I got this bug on all of them, and unchecking Host Resources fixed it on all of them

    WTF is going on? Very motivated to figure this one out. Nothing in logs regarding snmpd





  • @Grimson:

    https://redmine.pfsense.org/issues/6882

    Thanks, good to know I'm not crazy. I see in the comments they're getting it in vmware and kvm, I'll confirm its also happening in Xen


  • Rebel Alliance Global Moderator

    When I look at my settings doesn't even list hostres because it says not compatible with VM with cd/dvd drive..

    "The hostres module is not compatible with VMware virtual machines configured with a virtual CD/DVD Drive"




  • @johnpoz:

    When I look at my settings doesn't even list hostres because it says not compatible with VM with cd/dvd drive..

    "The hostres module is not compatible with VMware virtual machines configured with a virtual CD/DVD Drive"

    If you read the comments of the redmine bug you'll see they added detection for VMware where it removes the option proactively, however this hasn't been added to kvm and xen environments


  • Rebel Alliance Developer Netgate

    We had not had any reports of it yet on 2.4 snapshots but apparently this can also happen with physical CD drives and other drives as well. Disabling the hostres module should be enough to fix the problem if it is the same bug.

    We have our eyes on a FreeBSD patch that may fix it for 2.4.1 (coming out hopefully later this week) so hopefully not an issue for much longer.

    If disabling hostres is not enough and you need SNMP, then you can also try switching to the NET-SNMP package which is superior in nearly every way to bsnmpd except that it doesn't have direct access to pf stats like bsnmpd.



  • Thank you, guys!

    sds,