Re: [PATCH 7/7] block/rbd: change request alignment to 1 byte

[Peter Lieven]

Am 14.01.21 um 20:19 schrieb Jason Dillaman:
> On Sun, Dec 27, 2020 at 11:42 AM Peter Lieven <pl@kamp.de> wrote:
>> since we implement byte interfaces and librbd supports aio on byte 
>> granularity we can lift
>> the 512 byte alignment.
>>
>> Signed-off-by: Peter Lieven <pl@kamp.de>
>> ---
>>  block/rbd.c | 2 --
>>  1 file changed, 2 deletions(-)
>>
>> diff --git a/block/rbd.c b/block/rbd.c
>> index 27b4404adf..8673e8f553 100644
>> --- a/block/rbd.c
>> +++ b/block/rbd.c
>> @@ -223,8 +223,6 @@ done:
>>  static void qemu_rbd_refresh_limits(BlockDriverState *bs, Error **errp)
>>  {
>>      BDRVRBDState *s = bs->opaque;
>> -    /* XXX Does RBD support AIO on less than 512-byte alignment? */
>> -    bs->bl.request_alignment = 512;
> Just a suggestion, but perhaps improve discard alignment, max discard,
> optimal alignment (if that's something QEMU handles internally) if not
> overridden by the user.


Qemu supports max_discard and discard_alignment. Is there a call to get these 
limits

from librbd?


What do you mean by optimal_alignment? The object size?


Peter