Re: [PATCH v5 1/6] libnvdimm: nd_region flush callback support
On Thu, Apr 18, 2019 at 09:05:05AM -0700, Dan Williams wrote:
> > I'd either add a comment about avoiding retpoline
overhead here or just
> > make ->flush == NULL mean generic_nvdimm_flush(). Just so that people
don't
> > get confused by the code.
>
> Isn't this premature optimization? I really don't like adding things
> like this without some numbers to show it's worth it.
I don't think it's premature given this optimization technique is
already being deployed elsewhere, see:
https://lwn.net/Articles/774347/
For one this one was backed by numbers, and second after feedback
from Linux we switched to the NULL pointer check instead.