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Date:   Fri, 12 Apr 2019 10:32:30 +0200
From:   Jan Kara <jack@suse.cz>
To:     Dan Williams <dan.j.williams@intel.com>
Cc:     Pankaj Gupta <pagupta@redhat.com>,
        linux-nvdimm <linux-nvdimm@lists.01.org>,
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Subject: Re: [PATCH v5 1/6] libnvdimm: nd_region flush callback support
Message-ID: <20190412083230.GA29850@quack2.suse.cz>
References: <20190410040826.24371-1-pagupta@redhat.com>
 <20190410040826.24371-2-pagupta@redhat.com>
 <CAPcyv4i1FjBzfcWtzeCvj-giHa9xaX0dMQ==q4LZC_L8VEqkHg@mail.gmail.com>
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On Thu 11-04-19 07:51:48, Dan Williams wrote:
> On Tue, Apr 9, 2019 at 9:09 PM Pankaj Gupta <pagupta@redhat.com> 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 <jack@suse.com>
SUSE Labs, CR