Andre Guedes <andre.gue...@intel.com> writes: > Hi, > > Quoting Vinicius Costa Gomes (2020-05-15 18:29:44) >> One example, for retrieving and setting the configuration: >> >> $ ethtool $ sudo ./ethtool --show-frame-preemption enp3s0 >> Frame preemption settings for enp3s0: >> support: supported >> active: active > > IIUC the code in patch 2, 'active' is the actual configuration knob that > enables or disables the FP functionality on the NIC. > > That sounded a bit confusing to me since the spec uses the term 'active' to > indicate FP is currently enabled at both ends, and it is a read-only > information (see 12.30.1.4 from IEEE 802.1Q-2018). Maybe if we called this > 'enabled' it would be more clear.
Good point. Will rename this to "enabled". > >> supported queues: 0xf >> supported queues: 0xe >> minimum fragment size: 68 > > I'm assuming this is the configuration knob for the minimal non-final fragment > defined in 802.3br. > > My understanding from the specs is that this value must be a multiple from 64 > and cannot assume arbitrary values like shown here. See 99.4.7.3 from IEEE > 802.3 and Note 1 in S.2 from IEEE 802.1Q. In the previous discussion about FP, > we had this as a multiplier factor, not absolute value. I thought that exposing this as "(1 + N)*64" (with 0 <= N <= 3) that it was more related to what's exposed via LLDP than the actual capabilities of the hardware. And for the hardware I have actually the values supported are: (1 + N)*64 + 4 (for N = 0, 1, 2, 3). So I thought I was better to let the driver decide what values are acceptable. This is a good question for people working with other hardware. -- Vinicius
