Subject: Re: [PATCH] [RFC] allow admin/users to specify rto_min in milliseconds rather than jiffies

From: Rick Jones <[email-masked]>
Date: Wed, 12 Sep 2007 13:28:42 -0700

>> The api in netlink should be in milliseconds rather than compensating
>> in the application (iproute2).
> 
> 
> My understanding of the in-kernel rtnetlink code is far from complete, 
> but it doesn't seem to have much in the way of provisions for unit 
> conversion, which would suggest no nice suffix-based ui as in tc, and ip 
> is already doing some massaging of units on the display side for a 
> couple of the other parameters, so I'm at something of a loss.

So, I used the source and looked and saw that tc seems to convert 
everything to nanoseconds and passes that to the kernel.  The user can 
give it seconds, milliseconds, microseconds or nanoseconds by using a 
suffix. It then does something ostensibly intelligent to display those 
to the user.

Ip converts nothing when passing things to the kernel (rtt rttvar or rto 
- when/if at least the intial rto changes are included - were they?), 
but when they come-out of the kernel ip converts them to milliseconds. 
  So the units in != the units out.

Tc seems much more friendly and less prone to user error.

I'm still not sure how "easily" rtnetlink can do conversions itself - 
feedback there would be _very_ welcome - but at the very least, having 
ip provide at least the illusion of what tc does would seem to be a good 
thing.

rick jones