7.0-release / systat / 3GB
Kris Kennaway
kris at FreeBSD.org
Thu Jul 3 12:57:21 UTC 2008
Zbigniew Szalbot wrote:
> Hello,
>
> Kris Kennaway:
>> Wojciech Puchar wrote:
>>>> I am a bit curious though why once the outgoing bandwidth exceeds
>>>> (more or less) 3GB, the Total counter gets reset and starts counting
>>>> from scratch.
>>> isn't it 4GB - because of 32-bit unsigned counter?
>>
>> I would guess so.
>>
>> Using a 64-bit counter on 32-bit systems would cause additional
>> processing overhead for little benefit.
>
> I have confirmed (with assistance from Wojtek Puchar) that the problem
> of resetting a Total counter for 'systat -ifstat' happens every 4GB (not
> 3GB) amount of data. It only affects i386 machines. amd64 machines are
> not affected.
>
> I have tested this on 7.0 and 6.1-Release versions. Here's an example
>
> em0 in 104.564 KB/s 104.564 KB/s 2.401 GB
> out 220.282 KB/s 284.090 KB/s 3.874 GB
>
> em0 in 17.416 KB/s 220.306 KB/s 2.404 GB
> out 257.781 KB/s 284.090 KB/s 3.902 GB
>
> em0 in 35.181 KB/s 803.832 KB/s 2.420 GB
> out 170.575 KB/s 284.090 KB/s 3.980 GB
>
> em0 in 11.020 KB/s 803.832 KB/s 2.423 GB
> out 27.773 KB/s 284.090 KB/s 3.998 GB
>
> em0 in 5.515 KB/s 803.832 KB/s 2.423 GB
> out 97.953 KB/s 284.090 KB/s 4.000 GB
>
> em0 in 7.944 KB/s 803.832 KB/s 2.423 GB
> out 71.475 KB/s 284.090 KB/s 25.019 KB
>
> I have submitted a pr in case this can be fixed.
>
> http://www.freebsd.org/cgi/query-pr.cgi?pr=125196
I explained above why it cannot reasonably be fixed on i386 :-)
Kris
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