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Does anyone know what the sysmond application does on OS X? Lately it has been taking about 25-30% cpu constantly for no apparent reason.

Things I've tried so far:

  • Reboot
  • SMC reset
  • PRAM reset
  • Starting up in safe mode (sysmond also sucks up resources there)
  • Filesystem check (except for the regular incorrect directory count, no errors or whatever)

For the time being I've just disabled the sysmond plist but I guess it's not completely useless so I'm wondering what it's supposed to do and whether disabling is harmful ;)

enter image description here

Tomachi
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Wolph
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5 Answers5

60

What sysmond does on OS X

Watching the CPU usage of sysmond through Activity Monitor is pointless! It turns out that sysmond process is what Activity Monitor uses to get it's readings.

So if sysmond is using lots of CPU, just kill activity monitor for it to stop.

Warning

Increasing the update interval for Activity Monitor dramatically increases the CPU load, that's why I initially never noticed it and see it a lot more right now.

Wolph
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    Is this just speculation? Seeing higher CPU usage with Activity Monitor doesn't mean that's what it's supposed to do. – Navin Mar 10 '17 at 05:00
  • Unfortunately there appears to be virtually no official documentation but it appears the only logical conclusion. Even the sysmond man page says nothing beyond "system monitor daemon" which makes sense.

    So yes, it is speculation but is repeatable on all OS X systems I have encountered so far which makes it likely to be true.

     – Wolph Mar 10 '17 at 11:33
  • When I quit the Activity Monitor, then start it up again, the sysmond process's CPU Time has not changed. Which suggests that quitting the Activity Monitor does not end the sysmond process. – user5359531 Mar 23 '17 at 02:48
  • But it does suggest that the process does nothing if the activity monitor is not running. Since it has to run as root this is probably easier than starting and stopping the process. – Wolph Mar 23 '17 at 09:03
  • I double checked my Activity Monitor settings, and somehow the Update Frequency had gotten set to 'Very Often (1 sec)'. Not sure how this happened, but after setting it to 'Normally (5 sec)' the CPU usage of sysmond immediately dropped from ~25% to ~5%. – user5359531 Mar 29 '17 at 20:51
  • It turns out that even if you have Activity Monitor running (with no windows open), sysmond keeps running in the background. That means you should always quit Activity Monitor if you don't want to monitor anything anymore, instead of just closing all of its windows. – Oion Akif Apr 20 '17 at 10:02
  • when you say, “Increasing the update interval…” do you mean, “Decreasing the update interval…” ? – Chris F Carroll Apr 24 '18 at 16:16
  • @ChrisFCarroll: updates are apparently very heavy so by increasing the interval between the updates makes it less heavy on the machine. So no, I don't mean decrease :) – Wolph Apr 24 '18 at 19:58
  • Has anyone experiencing this so called issue, used htop or top to search for and monitor sysmond before, during and after using Activity Monitor? – Tmanok Feb 27 '19 at 03:31
  • @Tmanok yes I did, that's how I found the correlation between Activity Monitor and sysmond – Wolph Mar 01 '19 at 12:45
  • Just a note, sysmond is used for all system monitoring and as inferred here, it depends on which monitoring tool you use. Running htop will literally make sysmond use an ENTIRE CPU since it polls so many data points! – Darf Nader Mar 20 '20 at 02:20
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The high CPU usages seems related to the columns displayed. As soon as I turn on 'Real Shared Memory' or 'Real Private Memory' the CPU% of the sysmond process jumps from around 3% to above 30% and back again if none of the two is selected.

user376811
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This is what I found on my system

/usr/libexec/sysmond

/usr/share/man/man8/sysmond.8

/System/Library/LaunchDaemons/com.apple.sysmond.plist

It is described as some sort of system/files monitoring.

DESCRIPTION The sysmon.conf file is the main configuration file for the sysmond(man) which monitors systems and services on various machines connected to a network.

Ruskes
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    I've seen the man page, but it doesn't help much. Pretty much no description of what it actually does. – Wolph Apr 16 '14 at 15:29
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SYSMOND = System Monitor Daemon - monitors all system activity in background and automated by LaunchD (Launcher Daemon)

Billy Rubin
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1

I had the same problem. I tried quitting it with the Activity Monitor button, didn't quit. Then I force-quit it and Activity Monitor stopped updating.

Then I restarted Activity Monitor and it updated again, and sysmond is no longer taking lots of CPU (launchd automatically started a new process).

w00t
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