From: Jason Dillaman <jdillama@redhat.com>
To: Peter Lieven <pl@kamp.de>
Cc: Kevin Wolf <kwolf@redhat.com>,
Christian Theune <ct@flyingcircus.io>,
qemu-devel <qemu-devel@nongnu.org>,
qemu-block <qemu-block@nongnu.org>, Max Reitz <mreitz@redhat.com>
Subject: Re: [PATCH 7/7] block/rbd: change request alignment to 1 byte
Date: Fri, 15 Jan 2021 10:27:19 -0500 [thread overview]
Message-ID: <CA+aFP1Aayup5p482M8tsK3Zy62FLsfgUuQYnw_bSte-RuBrQXg@mail.gmail.com> (raw)
In-Reply-To: <f7358dc9-6135-dfa7-fd50-f863d0c8890a@kamp.de>
On Thu, Jan 14, 2021 at 2:59 PM Peter Lieven <pl@kamp.de> wrote:
>
> 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?
krbd does a good job of initializing defaults [1] where optimal and
discard alignment is 64KiB (can actually be 4KiB now), max IO size for
writes, discards, and write-zeroes is the object size * the stripe
count.
> Peter
>
>
>
[1] https://github.com/torvalds/linux/blob/master/drivers/block/rbd.c#L4981
--
Jason
next prev parent reply other threads:[~2021-01-15 15:30 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-27 16:42 [PATCH 0/7] block/rbd: migrate to coroutines and add write zeroes support Peter Lieven
2020-12-27 16:42 ` [PATCH 1/7] block/rbd: bump librbd requirement to luminous release Peter Lieven
2020-12-27 16:42 ` [PATCH 2/7] block/rbd: store object_size in BDRVRBDState Peter Lieven
2020-12-27 16:42 ` [PATCH 3/7] block/rbd: use stored image_size in qemu_rbd_getlength Peter Lieven
2021-01-14 19:18 ` Jason Dillaman
2021-01-14 19:32 ` Peter Lieven
2020-12-27 16:42 ` [PATCH 4/7] block/rbd: add bdrv_{attach,detach}_aio_context Peter Lieven
2021-01-14 19:18 ` Jason Dillaman
2021-01-14 19:49 ` Peter Lieven
2020-12-27 16:42 ` [PATCH 5/7] block/rbd: migrate from aio to coroutines Peter Lieven
2021-01-14 19:19 ` Jason Dillaman
2021-01-14 19:39 ` Peter Lieven
2020-12-27 16:42 ` [PATCH 6/7] block/rbd: add write zeroes support Peter Lieven
2021-01-14 19:19 ` Jason Dillaman
2021-01-14 19:41 ` Peter Lieven
2021-01-15 15:09 ` Jason Dillaman
2020-12-27 16:42 ` [PATCH 7/7] block/rbd: change request alignment to 1 byte Peter Lieven
2021-01-14 19:19 ` Jason Dillaman
2021-01-14 19:59 ` Peter Lieven
2021-01-15 15:27 ` Jason Dillaman [this message]
2021-01-15 15:39 ` Peter Lieven
2021-01-18 22:33 ` Jason Dillaman
2021-01-19 9:36 ` Peter Lieven
2021-01-19 14:20 ` Jason Dillaman
2021-01-20 23:01 Peter Lieven
2021-01-21 19:42 ` Jason Dillaman
2021-01-21 20:29 ` Peter Lieven
2021-01-21 20:55 ` Jason Dillaman
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