Re: [monit] Quad Core Monitoring

[Martin Pala]

Monit is reporting the CPU usage as total (corresponding to first 
example of top).

If the application will get 100% of one core on 4-core system, it's CPU 
usage should be reported by monit is 25% (since 4 * 25% = 100%).

You can thus use rule like this:

  if cpu usage > 25% then restart

Martin



address@hidden wrote:
> We have an issue were mysqld hogs up 100% of one of our cpu cores from 
> time to time.  How can I configure monit to restart mysqld when this 
> happens. 
>
> For an example of what I am talking about, top normally shows only one 
> cpu but if you press '1' it will show all the cpus.
> (normal top)
> top - 18:13:11 up 10 days, 21:59,  1 user,  load average: 1.56, 1.81, 2.08
> Tasks: 186 total,   5 running, 181 sleeping,   0 stopped,   0 zombie
> Cpu(s): 31.6% us,  7.6% sy,  0.0% ni, 60.8% id,  0.0% wa,  0.0% hi,  0.0% si
>
> (top after pressing '1')
> top - 18:13:54 up 10 days, 22:00,  1 user,  load average: 1.73, 1.81, 2.07
> Tasks: 185 total,   3 running, 182 sleeping,   0 stopped,   0 zombie
> Cpu0  : 29.4% us,  5.9% sy,  0.0% ni, 63.9% id,  0.7% wa,  0.0% hi,  0.0% si
> Cpu1  : 27.9% us,  5.6% sy,  0.0% ni, 65.5% id,  1.0% wa,  0.0% hi,  0.0% si
> Cpu2  : 23.1% us,  5.7% sy,  0.0% ni, 70.6% id,  0.7% wa,  0.0% hi,  0.0% si
> Cpu3  : 25.3% us,  6.2% sy,  0.0% ni, 67.5% id,  1.0% wa,  0.0% hi,  0.0% si
>
> (sample when mysqld is hogging cpu time)
> top - 18:13:54 up 10 days, 22:00,  1 user,  load average: 1.73, 1.81, 2.07
> Tasks: 185 total,   3 running, 182 sleeping,   0 stopped,   0 zombie
> Cpu0  : 100 % us,  5.9% sy,  0.0% ni, 63.9% id,  0.7% wa,  0.0% hi,  0.0% si
> Cpu1  : 7.9% us,  5.6% sy,  0.0% ni, 65.5% id,  1.0% wa,  0.0% hi,  0.0% si
> Cpu2  : 3.1% us,  5.7% sy,  0.0% ni, 70.6% id,  0.7% wa,  0.0% hi,  0.0% si
> Cpu3  : 5.3% us,  6.2% sy,  0.0% ni, 67.5% id,  1.0% wa,  0.0% hi,  0.0% si
>
> So, how do I get monit to restart mysqld when just one cpu is pegged at 
> 100%?  It's not always Cpu0, it could be any of them.
>
> Thanks,
>
>
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