Re: [Qemu-devel] [PATCH v5 1/6] libnvdimm: nd_region flush callback support

[Jan Kara]

On Thu 11-04-19 07:51:48, Dan Williams wrote:
> On Tue, Apr 9, 2019 at 9:09 PM Pankaj Gupta <address@hidden> wrote:
> > +       } else {
> > +               if (nd_region->flush(nd_region))
> > +                       rc = -EIO;
> 
> Given the common case wants to be fast and synchronous I think we
> should try to avoid retpoline overhead by default. So something like
> this:
> 
> if (nd_region->flush == generic_nvdimm_flush)
>     rc = generic_nvdimm_flush(...);

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.

                                                                Honza
-- 
Jan Kara <address@hidden>
SUSE Labs, CR