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Date: Fri, 18 Nov 2011 12:53:52 -0800
Message-ID: <CAFPOs6qGgmiaEdLHhmkZ7aQvjhv836-kiWXw5X22xt5cvmRtfw@mail.gmail.com>
From: Maksim Yevmenkin <maksim.yevmenkin@gmail.com>
To: Juli Mallett <jmallett@freebsd.org>
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Cc: freebsd-net <freebsd-net@freebsd.org>
Subject: Re: confused with if_baudrate
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On Thu, Nov 17, 2011 at 1:39 PM, Juli Mallett <jmallett@freebsd.org> wrote:
> On Thu, Nov 17, 2011 at 13:12, Maksim Yevmenkin
> <maksim.yevmenkin@gmail.com> wrote:
>> hello,
>>
>> i'm a little bit confused about if_baudrate. from system headers
>>
>> #define if_baudrate =A0 =A0 if_data.ifi_baudrate
>>
>> and
>>
>> u_long =A0ifi_baudrate; =A0 =A0 =A0 =A0 =A0 /* linespeed */
>>
>> so, i'm taking this as if_baudrate really should be an interface line
>> speed in megabits per second. am i correct? if so, then it appears
>> that at least some drivers lie about true line speed. for example from
>> ixgbe(4)
>>
>> =A0 =A0 =A0 =A0ifp->if_baudrate =3D 1000000000;
>>
>> it looks like its order of magnitude lower (i.e. 1 gigabit per second
>> instead of 10 gigabits per second). am i missing something here or its
>> just a typo?
>
> ixgbe's developer is excessively concerned about overflow on 32-bit
> hosts (and unwilling to correct it under a preprocessor conditional),
> unlike several of the other 10GbE driver developers, although I think
> one 10GbE driver opts to omit if_baudrate entirely.

well, this is unfortunate as if_baudrate reported as part of ifmib,
so, when interface is monitored over snmp value of ifSpeed and
HCOutSpeed can not be trusted :(

thanks,
max