Subject: Re: [RFC] RESEND - rdmatool - tool for RDMA users

From: Jason Gunthorpe <[email-masked]>
Date: Thu, 19 Jan 2017 15:16:51 -0700

On Thu, Jan 19, 2017 at 10:06:12PM +0000, Bart Van Assche wrote:
> On Thu, 2017-01-19 at 11:03 -0700, Jason Gunthorpe wrote:
> > sysfs is unpopular because the 'one value per file' dogma is laregly
> > unsuitable for complex mulit-value atomic changes which are common in
> > netdev. You can force it to work, but it is pretty horrible..
> > 
> > It is also very expensive if you want to shuttle a lot of data, eg I
> > could not see doing something like 'netstat' for IB through sysfs
> 
> Since the RDMA sysfs ABI defines a user space ABI and since user space
> ABIs must be backwards compatible removing the existing sysfs ABI is
> not an option. We will need to evaluate on a case-by-case basis whether
> new functionality should use sysfs or whether another mechanism should
> be used.

Not talking about getting rid of it.

But if it makes sense to use netlink for the new stuff we should make
netlink self-consistent so a netlink user does not have to fall back
to sysfs for certain things.

Jason