On Wed, Feb 05, 2025 at 09:09:58AM -0800, Jakub Kicinski wrote: > On Tue, 4 Feb 2025 17:26:43 +0000 Amit Cohen wrote: > > > > You're right, most of packets should be handled by HW, XDP is > > > > mainly useful for telemetry. > > > > > > Why skb path is not enough? > > > > We get better packet rates using XDP, this can be useful to redirect > > packets to a server for analysis for example. > > TBH I also feel a little ambivalent about adding advanced software > features to mlxsw. You have a dummy device off which you hang the NAPIs, > the page pools, and now the RXQ objects. That already works poorly with > our APIs. How are you going to handle the XDP side? Program per port, > I hope? But the basic fact remains that only fallback traffic goes thru > the XDP program which is not the normal Linux model, routing is after > XDP. > > On one hand it'd be great if upstream switch drivers could benefit from > the advanced features. On the other the HW is clearly not capable of > delivering in line with how NICs work, so we're signing up for a stream > of corner cases, bugs and incompatibility. Dunno. FWIIW, I do think that as this driver is actively maintained by the vendor, and this is a grey zone, it is reasonable to allow the vendor to decide if they want the burden of this complexity to gain some performance.
