High interrupt CPU usage in top

[Oliver Fromme]

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

-- 
Oliver Fromme,  secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing
Dienstleistungen mit Schwerpunkt FreeBSD: http://www.secnetix.de/bsd

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