On Sat, Mar 17, 2018 at 4:21 AM, Alex Elder <elder@xxxxxxxxxx> wrote:
> On 03/16/2018 07:37 AM, Alex Elder wrote:
>> From: Ilya Dryomov <idryomov@xxxxxxxxx>
>>
>> rbd needs this for null copyups -- if copyup data is all zeroes, we
>> want to save some I/O and network bandwidth. See rbd_obj_issue_copyup()
>> in the next commit.
>>
>> Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
>
> I don't think I realized you could advance a message by 0 bytes.
> I think it's not really intuitive, although I do think that
> encoding a 0-byte data item to mean implicitly zero-filled is
> a good convention. Anyway, I feel like there should be an
> explicit comment above ceph_msg_data_advance() to explain that
> would be good. (Maybe I've just forgotten about this, or maybe
> it's explained elsewhere...)
You couldn't previously. This is a new special case to optimize
rbd_obj_issue_copyup().
Thanks,
Ilya
--
To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
