On Sun, Feb 05, 2017 at 05:40:23PM +0100, Christoph Hellwig wrote: > Hi Joe, > > On Fri, Feb 03, 2017 at 08:58:09PM -0500, Joe Korty wrote: > > IIRC, some years ago I ran across a customer system where > > the #cpus_present was twice as big as #cpus_possible. > > > > Hyperthreading was turned off in the BIOS so it was not > > entirely out of line for the extra cpus to be declared > > present, even though none of them would ever be available > > for use. > > This sounds like a system we should quirk around instead of optimizing > for it. Unless I totally misunderstand the idea behind cpu_possible > and cpu_present. Can we use the online CPUs and create a new hot-cpu notifier to the nvme driver to free/reallocate as needed? We were doing that before blk-mq. Now blk-mq can change the number hardware contexts on a live queue, so we can reintroduce that behavior to nvme and only allocate what we need.
