On Fri, Oct 02, 2020 at 01:20:35PM -0700, Sagi Grimberg wrote: >> Well, why would they change it? The whole point of the infrastructure >> is that there is a single sane affinity setting for a given setup. Now >> that setting needed some refinement from the original series (e.g. the >> current series about only using housekeeping cpus if cpu isolation is >> in use). But allowing random users to modify affinity is just a receipe >> for a trainwreck. > > Well allowing people to mangle irq affinity settings seem to be a hard > requirement from the discussions in the past. > >> So I think we need to bring this back ASAP, as doing affinity right >> out of the box is an absolute requirement for sane performance without >> all the benchmarketing deep magic. > > Well, it's hard to say that setting custom irq affinity settings is > deemed non-useful to anyone and hence should be prevented. I'd expect > that irq settings have a sane default that works and if someone wants to > change it, it can but there should be no guarantees on optimal > performance. But IIRC this had some dependencies on drivers and some > more infrastructure to handle dynamic changes... The problem is that people change random settings. We need to generalize it into a sane API (e.g. the housekeeping CPUs thing which totally makes sense).
