On Fri 18-09-20 21:48:15, Uladzislau Rezki (Sony) wrote: [...] > Proposal > ======== > Introduce a lock-free function that obtain a page from the per-cpu-lists > on current CPU. It returns NULL rather than acquiring any non-raw spinlock. I was not happy about this solution when we have discussed this last time and I have to say I am still not happy. This is exposing an internal allocator optimization and allows a hard to estimate consumption of pcp free pages. IIUC this run on pcp cache can be controled directly from userspace (close(open) loop IIRC) which makes it even bigger no-no. I strongly agree with Thomas http://lkml.kernel.org/r/87tux4kefm.fsf@xxxxxxxxxxxxxxxxxxxxxxx that this optimization is not aiming at reasonable workloads. Really, go with pre-allocated buffer and fallback to whatever slow path you have already. Exposing more internals of the allocator is not going to do any good for long term maintainability. -- Michal Hocko SUSE Labs
