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Sun, 07 Dec 2025 08:58:41 -0500 X-MC-Unique: -wBmSFdfPeCIeX1UzphO3g-1 X-Mimecast-MFC-AGG-ID: -wBmSFdfPeCIeX1UzphO3g_1765115920 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 1898E1956053; Sun, 7 Dec 2025 13:58:40 +0000 (UTC) Received: from fedora (unknown [10.72.116.15]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id A6DD81800576; Sun, 7 Dec 2025 13:58:30 +0000 (UTC) Date: Sun, 7 Dec 2025 21:58:23 +0800 From: Ming Lei To: Caleb Sander Mateos Cc: Jens Axboe , linux-block@vger.kernel.org, Uday Shankar Subject: Re: [PATCH V5 10/21] ublk: add new feature UBLK_F_BATCH_IO Message-ID: References: <20251202121917.1412280-1-ming.lei@redhat.com> <20251202121917.1412280-11-ming.lei@redhat.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 On Sun, Dec 07, 2025 at 12:16:35AM -0800, Caleb Sander Mateos wrote: > On Tue, Dec 2, 2025 at 4:21 AM Ming Lei wrote: > > > > Add new feature UBLK_F_BATCH_IO which replaces the following two > > per-io commands: > > > > - UBLK_U_IO_FETCH_REQ > > > > - UBLK_U_IO_COMMIT_AND_FETCH_REQ > > > > with three per-queue batch io uring_cmd: > > > > - UBLK_U_IO_PREP_IO_CMDS > > > > - UBLK_U_IO_COMMIT_IO_CMDS > > > > - UBLK_U_IO_FETCH_IO_CMDS > > > > Then ublk can deliver batch io commands to ublk server in single > > multishort uring_cmd, also allows to prepare & commit multiple > > commands in batch style via single uring_cmd, communication cost is > > reduced a lot. > > > > This feature also doesn't limit task context any more for all supported > > commands, so any allowed uring_cmd can be issued in any task context. > > ublk server implementation becomes much easier. > > > > Meantime load balance becomes much easier to support with this feature. > > The command `UBLK_U_IO_FETCH_IO_CMDS` can be issued from multiple task > > contexts, so each task can adjust this command's buffer length or number > > of inflight commands for controlling how much load is handled by current > > task. > > > > Later, priority parameter will be added to command `UBLK_U_IO_FETCH_IO_CMDS` > > for improving load balance support. > > > > UBLK_U_IO_NEED_GET_DATA isn't supported in batch io yet, but it may be > > enabled in future via its batch pair. > > > > Signed-off-by: Ming Lei > > --- > > drivers/block/ublk_drv.c | 53 +++++++++++++++++++++++++++++------ > > include/uapi/linux/ublk_cmd.h | 16 +++++++++++ > > 2 files changed, 61 insertions(+), 8 deletions(-) > > > > diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c > > index 3865edabe1e6..034420e8df55 100644 > > --- a/drivers/block/ublk_drv.c > > +++ b/drivers/block/ublk_drv.c > > @@ -74,7 +74,8 @@ > > | UBLK_F_AUTO_BUF_REG \ > > | UBLK_F_QUIESCE \ > > | UBLK_F_PER_IO_DAEMON \ > > - | UBLK_F_BUF_REG_OFF_DAEMON) > > + | UBLK_F_BUF_REG_OFF_DAEMON \ > > + | UBLK_F_BATCH_IO) > > > > #define UBLK_F_ALL_RECOVERY_FLAGS (UBLK_F_USER_RECOVERY \ > > | UBLK_F_USER_RECOVERY_REISSUE \ > > @@ -331,12 +332,12 @@ static void ublk_batch_dispatch(struct ublk_queue *ubq, > > > > static inline bool ublk_dev_support_batch_io(const struct ublk_device *ub) > > { > > - return false; > > + return ub->dev_info.flags & UBLK_F_BATCH_IO; > > } > > > > static inline bool ublk_support_batch_io(const struct ublk_queue *ubq) > > { > > - return false; > > + return ubq->flags & UBLK_F_BATCH_IO; > > } > > > > static inline void ublk_io_lock(struct ublk_io *io) > > @@ -3462,6 +3463,35 @@ static int ublk_validate_batch_fetch_cmd(struct ublk_batch_io_data *data, > > return 0; > > } > > > > +static int ublk_handle_non_batch_cmd(struct io_uring_cmd *cmd, > > + unsigned int issue_flags) > > +{ > > + const struct ublksrv_io_cmd *ub_cmd = io_uring_sqe_cmd(cmd->sqe); > > + struct ublk_device *ub = cmd->file->private_data; > > + unsigned tag = READ_ONCE(ub_cmd->tag); > > + unsigned q_id = READ_ONCE(ub_cmd->q_id); > > + unsigned index = READ_ONCE(ub_cmd->addr); > > + struct ublk_queue *ubq; > > + struct ublk_io *io; > > + > > + if (cmd->cmd_op == UBLK_U_IO_UNREGISTER_IO_BUF) > > + return ublk_unregister_io_buf(cmd, ub, index, issue_flags); > > + > > + if (q_id >= ub->dev_info.nr_hw_queues) > > + return -EINVAL; > > + > > + if (tag >= ub->dev_info.queue_depth) > > + return -EINVAL; > > + > > + if (cmd->cmd_op != UBLK_U_IO_REGISTER_IO_BUF) > > + return -EOPNOTSUPP; > > + > > + ubq = ublk_get_queue(ub, q_id); > > + io = &ubq->ios[tag]; > > + return ublk_register_io_buf(cmd, ub, q_id, tag, io, index, > > + issue_flags); > > +} > > + > > static int ublk_ch_batch_io_uring_cmd(struct io_uring_cmd *cmd, > > unsigned int issue_flags) > > { > > @@ -3509,7 +3539,8 @@ static int ublk_ch_batch_io_uring_cmd(struct io_uring_cmd *cmd, > > ret = ublk_handle_batch_fetch_cmd(&data); > > break; > > default: > > - ret = -EOPNOTSUPP; > > + ret = ublk_handle_non_batch_cmd(cmd, issue_flags); > > It looks like the non-batch commands still perform the if > (data.header.q_id >= ub->dev_info.nr_hw_queues) check in > ublk_ch_batch_io_uring_cmd() even though they use struct > ublksrv_io_cmd instead of struct ublk_batch_io. I think it would be > preferable to move that check to ublk_check_batch_cmd() and > ublk_handle_batch_fetch_cmd(). Yes, will fix it in next version. > > > + break; > > } > > out: > > return ret; > > @@ -4179,10 +4210,9 @@ static int ublk_ctrl_add_dev(const struct ublksrv_ctrl_cmd *header) > > */ > > ub->dev_info.flags &= UBLK_F_ALL; > > > > - ub->dev_info.flags |= UBLK_F_CMD_IOCTL_ENCODE | > > - UBLK_F_URING_CMD_COMP_IN_TASK | > > - UBLK_F_PER_IO_DAEMON | > > - UBLK_F_BUF_REG_OFF_DAEMON; > > Why are these reported features removed? This will break ublk servers > that check for these features in the ublk device flags. oops, it is really one accident. Thanks, Ming