On Thu, Oct 27, 2016 at 7:38 PM, Tom Herbert <t...@herbertland.com> wrote: > On Thu, Oct 27, 2016 at 8:40 AM, Alexander Duyck > <alexander.h.du...@intel.com> wrote: >> This patch adds support for setting and using XPS when QoS via traffic >> classes is enabled. With this change we will factor in the priority and >> traffic class mapping of the packet and use that information to correctly >> select the queue. >> >> This allows us to define a set of queues for a given traffic class via >> mqprio and then configure the XPS mapping for those queues so that the >> traffic flows can avoid head-of-line blocking between the individual CPUs >> if so desired. >> > Does this change the sys API for XPS? Is it up the user to know which > are priority queues in sys?
The idea was to keep the change transparent. So for now the only change in relation to XPS from the XPS point of view is that the map for a given queue is invalidated when either the dev->num_tcs changes or if the queue is moved into a dev->tx_to_txq mapping. Otherwise the interface should behave exactly the same as before. One thing I could look at doing is adding a read-only sysfs value that the user could use to identify which traffic class a given queue belongs to. Then at least that way they would be able to dump both the XPS map and the tc to determine how the traffic will flow through the device. Thanks. - Alex
