vmstat -i weirdness

[tofik at oxygen.az]

> On Tue, Jan 02, 2007 at 02:08:44PM +0400, Tofik Suleymanov wrote:
>> Hello list,
>>
>> looks like `vmstat -i` acts weird on my machine after being 12-15 hours
>> uptime.Here is the iutput of `vmstat -i`:
>>
>> > vmstat -i
>> interrupt                          total       rate
>> irq1: atkbd0                        6813          0
>> irq9: acpi0                         5397          0
>> irq12: psm0                        73782          1
>> irq14: ata0                        74209          1
>> irq15: ata1                           47          0
>> irq18: uhci2                           1          0
>> irq19: uhci3 ehci0                     1          0
>> irq21: iwi0                        35139          0
>> cpu0: timer                    105315537       1999
>> Total                          105510926       2003
>> >
>>
>> Strange is that for example atkbd0 has rate of 0, but total interrupts
>> count of atkbd0 is growing.
>> Machine runs FreeBSD 6.1 RELEASE p11 with  pretty common  kernel.
>>
>> Is this known behaviour ?
>
> That is known and expected behaviour.  It is just a round-off error due to
> the use of integer division.
> 'rate' is the average number of interrupts/second calculated over the
> whole uptime of the machine.
> Since you probably press a key on the keyboard less than once per second
> (on
> average) this means that rate < 1 for atkbd0 and gets displayed as 0.
>
> If floating point values were used to display the rate you should see a
> value of maybe 0.13 for atkbd0.
>
>
> --
> <Insert your favourite quote here.>
> Erik Trulsson
> ertr1013 at student.uu.se
>

Erik,

that makes sense :)

Many thanks for explanation,
Tofig.