Re: [RFC PATCH] getcpu_cache system call: caching current CPU number (x86)

On Mon, Jul 13, 2015 at 8:27 AM, Mathieu Desnoyers
[off-list ref] wrote:

percpu segments will likely not solve everything. I have a use-case
with dynamically allocated per-cpu ring buffer in user-space (lttng-ust)
which can be a challenge for percpu segments. Having a fast getcpu()
is a win in those cases.

Note that percpu segments allow userspace to trivially implement fast getcpu.

For the record, Paul and I currently think the best solution is percpu
segments + some variant of a restart-sequence API (we'll have a patch
soon.)