High interrupt CPU usage in top

[Danial Thom]

--- Mark Cullen <mark.r.cullen at xxxxxxxxx> wrote:

> Oliver Fromme wrote:
> > Mark Cullen <mark.r.cullen at xxxxxxxxx> wrote:
> >  > I don't know if it is anything to be
> concerned about, but I seem to be 
> >  > seeing high interrupt CPU usage in top (at
> least) when compiling things...
> >  > 
> >  > ---
> >  > load averages:  0.81,  0.57,  0.36        
>              up 0+00:37:49 
> >  > 15:41:44
> >  > 43 processes:  2 running, 41 sleeping
> >  > CPU states: 37.1% user,  0.0% nice, 27.9%
> system, 35.0% interrupt,  0.0% idle
> > 
> > Have you tried "vmstat -i"?  It might give an
> indication
> > if any of the device interrupts is causing
> the problem.
> > 
> > I remember a similar problem on FreeBSD
> machines where the
> > USB interrupt was shared with the NIC
> interrupt.  The USB
> > interrupt handler is quite heavy-weight, so
> it slowed down
> > the processing of NIC interrupts, even if no
> actual USB
> > devices were in use at all.  Moving the USB
> controller to
> > a different interrupt (or disabling USB
> completely) solved
> > the problem.
> > 
> > Best regards
> >    Oliver
> > 
> 
> Yep, doesn't look particularly unusual to me
> (taken while compiling 
> multiple things)?
> 
> interrupt                   total       rate
> clk                       3134621        281
> atkbd0                       5405          0
> sio1                            0          0
> sio0                            0          0
> fxp0                       176854         15
> ppc0                            1          0
> acpi0                           0          0
> uhci0/fxp1                      0          0
> psm0                            0          0
> ata0                           40          0
> ata1                       250336         22
> irq19                          51          0
> swi_siopoll                     0          0
> swi_crypto/swi_camnet           0          0
> swi_cambio                      0          0
> swi_vm                          0          0
> swi_taskq                       0          0
> Total                     3567308        319
> 
> Looks like USB is sharing with fxp1? Not that
> fxp1 is actually even 
> plugged in or being used at all at the moment!!
> Unfortuantly disabling 
> USB is not an option for me, I have a USB ->
> Serial converter which I 
> need for the UPS.
> 
You'd have to do a delta as these are from system
startup:

Run "systat -vmstat 1" while compiling to see it
real-time to see where the fat is.

DT


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