From: Bart Van Assche <bvanassche@acm.org>
To: Danil Kipnis <danil.kipnis@cloud.ionos.com>
Cc: Jack Wang <jinpuwang@gmail.com>,
linux-block@vger.kernel.org, linux-rdma@vger.kernel.org,
Jens Axboe <axboe@kernel.dk>,
Christoph Hellwig <hch@infradead.org>,
Sagi Grimberg <sagi@grimberg.me>,
Jason Gunthorpe <jgg@mellanox.com>,
Doug Ledford <dledford@redhat.com>,
rpenyaev@suse.de, Jack Wang <jinpu.wang@cloud.ionos.com>,
Roman Pen <r.peniaev@gmail.com>
Subject: Re: [PATCH v4 17/25] ibnbd: client: main functionality
Date: Wed, 18 Sep 2019 08:47:29 -0700 [thread overview]
Message-ID: <6f677d56-82b3-a321-f338-cbf8ff4e83eb@acm.org> (raw)
In-Reply-To: <CAHg0HuzQOH4ZCe+v-GHu8jOYm-wUbh1fFRK75Muq+DPpQGAH8A@mail.gmail.com>
On 9/18/19 12:14 AM, Danil Kipnis wrote:
> I'm not familiar with dm code, but don't they need to deal with the
> same situation: if I configure 100 logical volumes on top of a single
> NVME drive with X hardware queues, each queue_depth deep, then each dm
> block device would need to advertise X hardware queues in order to
> achieve highest performance in case only this one volume is accessed,
> while in fact those X physical queues have to be shared among all 100
> logical volumes, if they are accessed in parallel?
Combining multiple queues (a) into a single queue (b) that is smaller
than the combined source queues without sacrificing performance is
tricky. We already have one such implementation in the block layer core
and it took considerable time to get that implementation right. See e.g.
blk_mq_sched_mark_restart_hctx() and blk_mq_sched_restart().
dm drivers are expected to return DM_MAPIO_REQUEUE or
DM_MAPIO_DELAY_REQUEUE if the queue (b) is full. It turned out to be
difficult to get this right in the dm-mpath driver and at the same time
to achieve good performance.
The ibnbd driver introduces a third implementation of code that combines
multiple (per-cpu) queues into one queue per CPU. It is considered
important in the Linux kernel to avoid code duplication. Hence my
question whether ibnbd can reuse the block layer infrastructure for
sharing tag sets.
Thanks,
Bart.
next prev parent reply other threads:[~2019-09-18 15:47 UTC|newest]
Thread overview: 148+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-20 15:03 [PATCH v4 00/25] InfiniBand Transport (IBTRS) and Network Block Device (IBNBD) Jack Wang
2019-06-20 15:03 ` [PATCH v4 01/25] sysfs: export sysfs_remove_file_self() Jack Wang
2019-09-23 17:21 ` Bart Van Assche
2019-09-25 9:30 ` Danil Kipnis
2019-06-20 15:03 ` [PATCH v4 02/25] ibtrs: public interface header to establish RDMA connections Jack Wang
2019-09-23 17:44 ` Bart Van Assche
2019-09-25 10:20 ` Danil Kipnis
2019-09-25 15:38 ` Bart Van Assche
2019-06-20 15:03 ` [PATCH v4 03/25] ibtrs: private headers with IBTRS protocol structs and helpers Jack Wang
2019-09-23 22:50 ` Bart Van Assche
2019-09-25 21:45 ` Danil Kipnis
2019-09-25 21:57 ` Bart Van Assche
2019-09-27 8:56 ` Jinpu Wang
2019-06-20 15:03 ` [PATCH v4 04/25] ibtrs: core: lib functions shared between client and server modules Jack Wang
2019-09-23 23:03 ` Bart Van Assche
2019-09-27 10:13 ` Jinpu Wang
2019-06-20 15:03 ` [PATCH v4 05/25] ibtrs: client: private header with client structs and functions Jack Wang
2019-09-23 23:05 ` Bart Van Assche
2019-09-27 10:18 ` Jinpu Wang
2019-06-20 15:03 ` [PATCH v4 06/25] ibtrs: client: main functionality Jack Wang
2019-09-23 21:51 ` Bart Van Assche
2019-09-25 17:36 ` Danil Kipnis
2019-09-25 18:55 ` Bart Van Assche
2019-09-25 20:50 ` Danil Kipnis
2019-09-25 21:08 ` Bart Van Assche
2019-09-25 21:16 ` Bart Van Assche
2019-09-25 22:53 ` Danil Kipnis
2019-09-25 23:21 ` Bart Van Assche
2019-09-26 9:16 ` Danil Kipnis
2019-06-20 15:03 ` [PATCH v4 07/25] ibtrs: client: statistics functions Jack Wang
2019-09-23 23:15 ` Bart Van Assche
2019-09-27 12:00 ` Jinpu Wang
2019-06-20 15:03 ` [PATCH v4 08/25] ibtrs: client: sysfs interface functions Jack Wang
2019-06-20 15:03 ` [PATCH v4 09/25] ibtrs: server: private header with server structs and functions Jack Wang
2019-09-23 23:21 ` Bart Van Assche
2019-09-27 12:04 ` Jinpu Wang
2019-06-20 15:03 ` [PATCH v4 10/25] ibtrs: server: main functionality Jack Wang
2019-09-23 23:49 ` Bart Van Assche
2019-09-27 15:03 ` Jinpu Wang
2019-09-27 15:11 ` Bart Van Assche
2019-09-27 15:19 ` Jinpu Wang
2019-06-20 15:03 ` [PATCH v4 11/25] ibtrs: server: statistics functions Jack Wang
2019-09-23 23:56 ` Bart Van Assche
2019-10-02 15:15 ` Jinpu Wang
2019-10-02 15:42 ` Leon Romanovsky
2019-10-02 15:45 ` Jinpu Wang
2019-10-02 16:00 ` Leon Romanovsky
2019-06-20 15:03 ` [PATCH v4 12/25] ibtrs: server: sysfs interface functions Jack Wang
2019-09-24 0:00 ` Bart Van Assche
2019-10-02 15:11 ` Jinpu Wang
2019-06-20 15:03 ` [PATCH v4 13/25] ibtrs: include client and server modules into kernel compilation Jack Wang
2019-06-20 15:03 ` [PATCH v4 14/25] ibtrs: a bit of documentation Jack Wang
2019-06-20 15:03 ` [PATCH v4 15/25] ibnbd: private headers with IBNBD protocol structs and helpers Jack Wang
2019-09-13 22:10 ` Bart Van Assche
2019-09-15 14:30 ` Jinpu Wang
2019-09-16 5:27 ` Leon Romanovsky
2019-09-16 13:45 ` Bart Van Assche
2019-09-17 15:41 ` Leon Romanovsky
2019-09-17 15:52 ` Jinpu Wang
2019-09-16 7:08 ` Danil Kipnis
2019-09-16 14:57 ` Jinpu Wang
2019-09-16 17:25 ` Bart Van Assche
2019-09-17 12:27 ` Jinpu Wang
2019-09-16 15:39 ` Jinpu Wang
2019-09-18 15:26 ` Bart Van Assche
2019-09-18 16:11 ` Jinpu Wang
2019-06-20 15:03 ` [PATCH v4 16/25] ibnbd: client: private header with client structs and functions Jack Wang
2019-09-13 22:25 ` Bart Van Assche
2019-09-17 16:36 ` Jinpu Wang
2019-09-25 23:43 ` Danil Kipnis
2019-09-26 10:00 ` Jinpu Wang
2019-06-20 15:03 ` [PATCH v4 17/25] ibnbd: client: main functionality Jack Wang
2019-09-13 23:46 ` Bart Van Assche
2019-09-16 14:17 ` Danil Kipnis
2019-09-16 16:46 ` Bart Van Assche
2019-09-17 11:39 ` Danil Kipnis
2019-09-18 7:14 ` Danil Kipnis
2019-09-18 15:47 ` Bart Van Assche [this message]
2019-09-20 8:29 ` Danil Kipnis
2019-09-25 22:26 ` Danil Kipnis
2019-09-26 9:55 ` Roman Penyaev
2019-09-26 15:01 ` Bart Van Assche
2019-09-27 8:52 ` Roman Penyaev
2019-09-27 9:32 ` Danil Kipnis
2019-09-27 12:18 ` Danil Kipnis
2019-09-27 16:37 ` Bart Van Assche
2019-09-27 16:50 ` Roman Penyaev
2019-09-27 17:16 ` Bart Van Assche
2019-09-17 13:09 ` Jinpu Wang
2019-09-17 16:46 ` Bart Van Assche
2019-09-18 12:02 ` Jinpu Wang
2019-09-18 16:05 ` Jinpu Wang
2019-09-14 0:00 ` Bart Van Assche
2019-06-20 15:03 ` [PATCH v4 18/25] ibnbd: client: sysfs interface functions Jack Wang
2019-09-18 16:28 ` Bart Van Assche
2019-09-19 15:55 ` Jinpu Wang
2019-06-20 15:03 ` [PATCH v4 19/25] ibnbd: server: private header with server structs and functions Jack Wang
2019-06-20 15:03 ` [PATCH v4 20/25] ibnbd: server: main functionality Jack Wang
2019-09-18 17:41 ` Bart Van Assche
2019-09-20 7:36 ` Danil Kipnis
2019-09-20 15:42 ` Bart Van Assche
2019-09-23 15:19 ` Danil Kipnis
2019-06-20 15:03 ` [PATCH v4 21/25] ibnbd: server: functionality for IO submission to file or block dev Jack Wang
2019-09-18 21:46 ` Bart Van Assche
2019-09-26 14:04 ` Jinpu Wang
2019-09-26 15:11 ` Bart Van Assche
2019-09-26 15:25 ` Danil Kipnis
2019-09-26 15:29 ` Bart Van Assche
2019-09-26 15:38 ` Danil Kipnis
2019-09-26 15:42 ` Jinpu Wang
2019-06-20 15:03 ` [PATCH v4 22/25] ibnbd: server: sysfs interface functions Jack Wang
2019-06-20 15:03 ` [PATCH v4 23/25] ibnbd: include client and server modules into kernel compilation Jack Wang
2019-06-20 15:03 ` [PATCH v4 24/25] ibnbd: a bit of documentation Jack Wang
2019-09-13 23:58 ` Bart Van Assche
2019-09-18 12:22 ` Jinpu Wang
2019-06-20 15:03 ` [PATCH v4 25/25] MAINTAINERS: Add maintainer for IBNBD/IBTRS modules Jack Wang
2019-07-09 15:10 ` Leon Romanovsky
2019-07-09 15:18 ` Jinpu Wang
2019-07-09 15:51 ` Leon Romanovsky
2019-09-13 23:56 ` Bart Van Assche
2019-09-19 10:30 ` Jinpu Wang
2019-07-09 9:55 ` [PATCH v4 00/25] InfiniBand Transport (IBTRS) and Network Block Device (IBNBD) Danil Kipnis
2019-07-09 11:00 ` Leon Romanovsky
2019-07-09 11:17 ` Greg KH
2019-07-09 11:57 ` Jinpu Wang
2019-07-09 13:32 ` Leon Romanovsky
2019-07-09 15:39 ` Bart Van Assche
2019-07-09 11:37 ` Jinpu Wang
2019-07-09 12:06 ` Jason Gunthorpe
2019-07-09 13:15 ` Jinpu Wang
2019-07-09 13:19 ` Jason Gunthorpe
2019-07-09 14:17 ` Jinpu Wang
2019-07-09 21:27 ` Sagi Grimberg
2019-07-19 13:12 ` Danil Kipnis
2019-07-10 14:55 ` Danil Kipnis
2019-07-09 12:04 ` Jason Gunthorpe
2019-07-09 19:45 ` Sagi Grimberg
2019-07-10 13:55 ` Jason Gunthorpe
2019-07-10 16:25 ` Sagi Grimberg
2019-07-10 17:25 ` Jason Gunthorpe
2019-07-10 19:11 ` Sagi Grimberg
2019-07-11 7:27 ` Danil Kipnis
2019-07-11 8:54 ` Danil Kipnis
2019-07-12 0:22 ` Sagi Grimberg
2019-07-12 7:57 ` Jinpu Wang
2019-07-12 19:40 ` Sagi Grimberg
2019-07-15 11:21 ` Jinpu Wang
2019-07-12 10:58 ` Danil Kipnis
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