From: Danil Kipnis <danil.kipnis@cloud.ionos.com>
To: Roman Penyaev <r.peniaev@gmail.com>
Cc: Bart Van Assche <bvanassche@acm.org>,
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>
Subject: Re: [PATCH v4 17/25] ibnbd: client: main functionality
Date: Fri, 27 Sep 2019 11:32:44 +0200 [thread overview]
Message-ID: <CAHg0HuwgPXtaY3XGv0=TjPbmRRdbmOsa7fRYa+n5fGf9K0_xRg@mail.gmail.com> (raw)
In-Reply-To: <CACZ9PQU8=4DaSAUQ7czKdcWio2H5HB1ro-pXaY2VP9PhgTxk7g@mail.gmail.com>
On Fri, Sep 27, 2019 at 10:52 AM Roman Penyaev <r.peniaev@gmail.com> wrote:
>
> No, it seems this thingy is a bit different. According to my
> understanding patches 3 and 4 from this patchset do the
> following: 1# split equally the whole queue depth on number
> of hardware queues and 2# return tag number which is unique
> host-wide (more or less similar to unique_tag, right?).
>
> 2# is not needed for ibtrs, and 1# can be easy done by dividing
> queue_depth on number of hw queues on tag set allocation, e.g.
> something like the following:
>
> ...
> tags->nr_hw_queues = num_online_cpus();
> tags->queue_depth = sess->queue_deph / tags->nr_hw_queues;
>
> blk_mq_alloc_tag_set(tags);
>
>
> And this trick won't work out for the performance. ibtrs client
> has a single resource: set of buffer chunks received from a
> server side. And these buffers should be dynamically distributed
> between IO producers according to the load. Having a hard split
> of the whole queue depth between hw queues we can forget about a
> dynamic load distribution, here is an example:
>
> - say server shares 1024 buffer chunks for a session (do not
> remember what is the actual number).
>
> - 1024 buffers are equally divided between hw queues, let's
> say 64 (number of cpus), so each queue is 16 requests depth.
>
> - only several CPUs produce IO, and instead of occupying the
> whole "bandwidth" of a session, i.e. 1024 buffer chunks,
> we limit ourselves to a small queue depth of an each hw
> queue.
>
> And performance drops significantly when number of IO producers
> is smaller than number of hw queues (CPUs), and it can be easily
> tested and proved.
>
> So for this particular ibtrs case tags should be globally shared,
> and seems (unfortunately) there is no any other similar requirements
> for other block devices.
I don't see any difference between what you describe here and 100 dm
volumes sitting on top of a single NVME device.
next prev parent reply other threads:[~2019-09-27 9:32 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
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 [this message]
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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