The IEEE Std 802.1Q specs for credit-based shaper require precise transmit decisions within a 125 microsecond window of time.
Even with the Preempt RT patch or similar enhancements, that isn't very practical as software-only. I doubt that software would conform to the standard's requirements. This is analogous to memory, or CPU. . > -----Original Message----- > From: David Miller [mailto:[email protected]] > Sent: Thursday, October 5, 2017 1:29 PM > To: [email protected] > Cc: [email protected]; [email protected]; [email protected]; > [email protected]; [email protected]; > [email protected]; [email protected]; [email protected]; > [email protected]; [email protected]; > [email protected]; [email protected]; Rodney Cummings > <[email protected]> > Subject: Re: [next-queue PATCH v4 3/4] net/sched: Introduce Credit Based > Shaper (CBS) qdisc > > From: Levi Pearson <[email protected]> > Date: Thu, 5 Oct 2017 12:09:32 -0600 > > > It would be a shame if this were blocked due to a missing software > > implementation. > > Quite the contrary, I think a software implementation is a minimum > requirement for inclusion of this feature. > > Without a software implementation, there is no clear definition of > what is supposed to happen, and no clear way for people to test those > expectations unless they have the specific hardware. > > I completely agree with Jiri. Hardware offload first is _not_ how > we do things in the Linux networking.
