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(pl@kamp.de@::ffff:172.20.250.14) by submission.kamp.de with ESMTPS (DHE-RSA-AES128-SHA encrypted) ESMTPA; 14 Jan 2021 19:41:48 -0000 Subject: Re: [PATCH 6/7] block/rbd: add write zeroes support To: dillaman@redhat.com References: <20201227164236.10143-1-pl@kamp.de> <20201227164236.10143-7-pl@kamp.de> From: Peter Lieven Message-ID: <2449ab2d-e9da-6e4e-7de5-8dd23501d27e@kamp.de> Date: Thu, 14 Jan 2021 20:41:47 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US Received-SPF: pass client-ip=195.62.97.192; envelope-from=pl@kamp.de; helo=kerio.kamp.de X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, NICE_REPLY_A=-0.237, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Christian Theune , qemu-devel , qemu-block , Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 14.01.21 um 20:19 schrieb Jason Dillaman: > On Sun, Dec 27, 2020 at 11:42 AM Peter Lieven wrote: >> Signed-off-by: Peter Lieven >> --- >> block/rbd.c | 31 ++++++++++++++++++++++++++++++- >> 1 file changed, 30 insertions(+), 1 deletion(-) >> >> diff --git a/block/rbd.c b/block/rbd.c >> index 2d77d0007f..27b4404adf 100644 >> --- a/block/rbd.c >> +++ b/block/rbd.c >> @@ -63,7 +63,8 @@ typedef enum { >> RBD_AIO_READ, >> RBD_AIO_WRITE, >> RBD_AIO_DISCARD, >> - RBD_AIO_FLUSH >> + RBD_AIO_FLUSH, >> + RBD_AIO_WRITE_ZEROES >> } RBDAIOCmd; >> >> typedef struct BDRVRBDState { >> @@ -221,8 +222,12 @@ 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; >> +#ifdef LIBRBD_SUPPORTS_WRITE_ZEROES >> + bs->bl.pwrite_zeroes_alignment = s->object_size; > The optimal alignment is 512 bytes -- but it can safely work just fine > down to 1 byte alignment since it will pad the request with additional > writes if needed. Okay and this will likely be faster than having Qemu doing that request split, right? If we drop the alignment hint Qemu will pass the original request. > >> +#endif >> } >> >> >> @@ -695,6 +700,9 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict *options, int flags, >> } >> >> s->aio_context = bdrv_get_aio_context(bs); >> +#ifdef LIBRBD_SUPPORTS_WRITE_ZEROES >> + bs->supported_zero_flags = BDRV_REQ_MAY_UNMAP; >> +#endif >> >> /* When extending regular files, we get zeros from the OS */ >> bs->supported_truncate_flags = BDRV_REQ_ZERO_WRITE; >> @@ -808,6 +816,11 @@ static int coroutine_fn qemu_rbd_start_co(BlockDriverState *bs, >> case RBD_AIO_FLUSH: >> r = rbd_aio_flush(s->image, c); >> break; >> +#ifdef LIBRBD_SUPPORTS_WRITE_ZEROES >> + case RBD_AIO_WRITE_ZEROES: >> + r = rbd_aio_write_zeroes(s->image, offset, bytes, c, 0, 0); >> + break; >> +#endif >> default: >> r = -EINVAL; >> } >> @@ -880,6 +893,19 @@ static int coroutine_fn qemu_rbd_co_pdiscard(BlockDriverState *bs, >> return qemu_rbd_start_co(bs, offset, count, NULL, 0, RBD_AIO_DISCARD); >> } >> >> +#ifdef LIBRBD_SUPPORTS_WRITE_ZEROES >> +static int >> +coroutine_fn qemu_rbd_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset, >> + int count, BdrvRequestFlags flags) >> +{ >> + if (!(flags & BDRV_REQ_MAY_UNMAP)) { >> + return -ENOTSUP; >> + } > There is a "RBD_WRITE_ZEROES_FLAG_THICK_PROVISION" flag that you can > use to optionally disable unmap. I have seen that. If you want I can support for this, too. But afaik this is only available since Octopus release? Peter