RE: [PATCH v3] mmc: rtsx: improve performance for multi block rw

Ricky WU
2023-10-13T02:27:22Z

> On Wed, 11 Oct 2023 at 07:36, Ricky WU <ricky_wu@realtek.com> wrote:
> >
> > Hi Ulf Hansson,
> >
> > Can I know what is this patch status or has some concern on this patch?
>
> Didn't you read my earlier replies?
>

Are you talking about BFQ for testing speed?
Because we tested the Read/Write speed are better than before and our customer that uses our reader on their product also tested the Read/Write speed, they want us to push this patch on

> Kind regards
> Uffe
>
> >
> > Ricky
> > > -----Original Message-----
> > > From: Ulf Hansson <ulf.hansson@linaro.org>
> > > Sent: Thursday, February 10, 2022 10:57 PM
> > > To: Ricky WU <ricky_wu@realtek.com>
> > > Cc: tommyhebb@gmail.com; linux-mmc@vger.kernel.org;
> > > linux-kernel@vger.kernel.org
> > > Subject: Re: [PATCH v3] mmc: rtsx: improve performance for multi block rw
> > >
> > > On Thu, 10 Feb 2022 at 07:43, Ricky WU <ricky_wu@realtek.com> wrote:
> > > >
> > > >
> > > >
> > > > > -----Original Message-----
> > > > > From: Ulf Hansson <ulf.hansson@linaro.org>
> > > > > Sent: Monday, February 7, 2022 7:11 PM
> > > > > To: Ricky WU <ricky_wu@realtek.com>
> > > > > Cc: tommyhebb@gmail.com; linux-mmc@vger.kernel.org;
> > > > > linux-kernel@vger.kernel.org
> > > > > Subject: Re: [PATCH v3] mmc: rtsx: improve performance for multi
> > > > > block rw
> > > > >
> > > > > [...]
> > > > >
> > > > > > > > > >
> > > > > > > > > > Do you have any suggestion for testing random I/O But we
> > > > > > > > > > think random I/O will not change much
> > > > > > > > >
> > > > > > > > > I would probably look into using fio,
> > > > > > > > > https://fio.readthedocs.io/en/latest/
> > > > > > > > >
> > > > > > > >
> > > > > > > > Filled random I/O data
> > > > > > > > Before the patch:
> > > > > > > > CMD (Randread):
> > > > > > > > sudo fio -filename=/dev/mmcblk0 -direct=1 -numjobs=1 -thread
> > > > > > > > -group_reporting -ioengine=psync -iodepth=1 -size=1G
> > > > > > > > -name=mytest -bs=1M -rw=randread
> > > > > > >
> > > > > > > Thanks for running the tests! Overall, I would not expect an
> > > > > > > impact on the throughput when using a big blocksize like 1M.
> > > > > > > This is also pretty clear from the result you have provided.
> > > > > > >
> > > > > > > However, especially for random writes and reads, we want to try
> > > > > > > with smaller blocksizes. Like 8k or 16k, would you mind running
> > > > > > > another round of tests to see how that works out?
> > > > > > >
> > > > > >
> > > > > > Filled random I/O data(8k/16k)
> > > > >
> > > > > Hi Ricky,
> > > > >
> > > > > Apologize for the delay! Thanks for running the tests. Let me
> > > > > comment on them below.
> > > > >
> > > > > >
> > > > > > Before(randread)
> > > > > > 8k:
> > > > > > Cmd: sudo fio -filename=/dev/mmcblk0 -direct=1 -numjobs=1 -thread
> > > > > > -group_reporting -ioengine=psync -iodepth=1 -size=1G -name=mytest
> > > > > > -bs=8k -rw=randread
> > > > > > mytest: (g=0): rw=randread, bs=(R) 8192B-8192B, (W) 8192B-8192B,
> > > > > > (T) 8192B-8192B, ioengine=psync, iodepth=1
> > > > > > result:
> > > > > > Run status group 0 (all jobs):
> > > > > > READ: bw=16.5MiB/s (17.3MB/s), 16.5MiB/s-16.5MiB/s
> > > > > > (17.3MB/s-17.3MB/s), io=1024MiB (1074MB),
> run=62019-62019msec
> > > Disk
> > > > > stats (read/write):
> > > > > > mmcblk0: ios=130757/0, merge=0/0, ticks=57751/0,
> in_queue=57751,
> > > > > > util=99.89%
> > > > > >
> > > > > > 16k:
> > > > > > Cmd: sudo fio -filename=/dev/mmcblk0 -direct=1 -numjobs=1 -thread
> > > > > > -group_reporting -ioengine=psync -iodepth=1 -size=1G -name=mytest
> > > > > > -bs=16k -rw=randread
> > > > > > mytest: (g=0): rw=randread, bs=(R) 16.0KiB-16.0KiB, (W)
> > > > > > 16.0KiB-16.0KiB, (T) 16.0KiB-16.0KiB, ioengine=psync, iodepth=1
> > > > > > result:
> > > > > > Run status group 0 (all jobs):
> > > > > > READ: bw=23.3MiB/s (24.4MB/s), 23.3MiB/s-23.3MiB/s
> > > > > > (24.4MB/s-24.4MB/s), io=1024MiB (1074MB),
> run=44034-44034msec
> > > Disk
> > > > > stats (read/write):
> > > > > > mmcblk0: ios=65333/0, merge=0/0, ticks=39420/0,
> in_queue=39420,
> > > > > > util=99.84%
> > > > > >
> > > > > > Before(randrwrite)
> > > > > > 8k:
> > > > > > Cmd: sudo fio -filename=/dev/mmcblk0 -direct=1 -numjobs=1 -thread
> > > > > > -group_reporting -ioengine=psync -iodepth=1 -size=100M
> > > > > > -name=mytest -bs=8k -rw=randwrite
> > > > > > mytest: (g=0): rw=randwrite, bs=(R) 8192B-8192B, (W) 8192B-8192B,
> > > > > > (T) 8192B-8192B, ioengine=psync, iodepth=1
> > > > > > result:
> > > > > > Run status group 0 (all jobs):
> > > > > > WRITE: bw=4060KiB/s (4158kB/s), 4060KiB/s-4060KiB/s
> > > > > > (4158kB/s-4158kB/s), io=100MiB (105MB), run=25220-25220msec
> Disk
> > > > > > stats
> > > > > (read/write):
> > > > > > mmcblk0: ios=51/12759, merge=0/0, ticks=80/24154,
> > > > > > in_queue=24234, util=99.90%
> > > > > >
> > > > > > 16k:
> > > > > > Cmd: sudo fio -filename=/dev/mmcblk0 -direct=1 -numjobs=1 -thread
> > > > > > -group_reporting -ioengine=psync -iodepth=1 -size=100M
> > > > > > -name=mytest -bs=16k -rw=randwrite
> > > > > > mytest: (g=0): rw=randwrite, bs=(R) 16.0KiB-16.0KiB, (W)
> > > > > > 16.0KiB-16.0KiB, (T) 16.0KiB-16.0KiB, ioengine=psync, iodepth=1
> > > > > > result:
> > > > > > Run status group 0 (all jobs):
> > > > > > WRITE: bw=7201KiB/s (7373kB/s), 7201KiB/s-7201KiB/s
> > > > > > (7373kB/s-7373kB/s), io=100MiB (105MB), run=14221-14221msec
> Disk
> > > > > > stats
> > > > > (read/write):
> > > > > > mmcblk0: ios=51/6367, merge=0/0, ticks=82/13647,
> in_queue=13728,
> > > > > > util=99.81%
> > > > > >
> > > > > >
> > > > > > After(randread)
> > > > > > 8k:
> > > > > > Cmd: sudo fio -filename=/dev/mmcblk0 -direct=1 -numjobs=1 -thread
> > > > > > -group_reporting -ioengine=psync -iodepth=1 -size=1G -name=mytest
> > > > > > -bs=8k -rw=randread
> > > > > > mytest: (g=0): rw=randread, bs=(R) 8192B-8192B, (W) 8192B-8192B,
> > > > > > (T) 8192B-8192B, ioengine=psync, iodepth=1
> > > > > > result:
> > > > > > Run status group 0 (all jobs):
> > > > > > READ: bw=12.4MiB/s (13.0MB/s), 12.4MiB/s-12.4MiB/s
> > > > > > (13.0MB/s-13.0MB/s), io=1024MiB (1074MB),
> run=82397-82397msec
> > > Disk
> > > > > stats (read/write):
> > > > > > mmcblk0: ios=130640/0, merge=0/0, ticks=74125/0,
> in_queue=74125,
> > > > > > util=99.94%
> > > > > >
> > > > > > 16k:
> > > > > > Cmd: sudo fio -filename=/dev/mmcblk0 -direct=1 -numjobs=1 -thread
> > > > > > -group_reporting -ioengine=psync -iodepth=1 -size=1G -name=mytest
> > > > > > -bs=16k -rw=randread
> > > > > > mytest: (g=0): rw=randread, bs=(R) 16.0KiB-16.0KiB, (W)
> > > > > > 16.0KiB-16.0KiB, (T) 16.0KiB-16.0KiB, ioengine=psync, iodepth=1
> > > > > > result:
> > > > > > Run status group 0 (all jobs):
> > > > > > READ: bw=20.0MiB/s (21.0MB/s), 20.0MiB/s-20.0MiB/s
> > > > > > (21.0MB/s-21.0MB/s), io=1024MiB (1074MB),
> run=51076-51076msec
> > > Disk
> > > > > stats (read/write):
> > > > > > mmcblk0: ios=65282/0, merge=0/0, ticks=46255/0,
> in_queue=46254,
> > > > > > util=99.87%
> > > > > >
> > > > > > After(randwrite)
> > > > > > 8k:
> > > > > > Cmd: sudo fio -filename=/dev/mmcblk0 -direct=1 -numjobs=1 -thread
> > > > > > -group_reporting -ioengine=psync -iodepth=1 -size=100M
> > > > > > -name=mytest -bs=8k -rw=randwrite
> > > > > > mytest: (g=0): rw=randwrite, bs=(R) 8192B-8192B, (W) 8192B-8192B,
> > > > > > (T) 8192B-8192B, ioengine=psync, iodepth=1
> > > > > > result:
> > > > > > Run status group 0 (all jobs):
> > > > > > WRITE: bw=4215KiB/s (4317kB/s), 4215KiB/s-4215KiB/s
> > > > > > (4317kB/s-4317kB/s), io=100MiB (105MB), run=24292-24292msec
> Disk
> > > > > > stats
> > > > > (read/write):
> > > > > > mmcblk0: ios=52/12717, merge=0/0, ticks=86/23182,
> > > > > > in_queue=23267, util=99.92%
> > > > > >
> > > > > > 16k:
> > > > > > Cmd: sudo fio -filename=/dev/mmcblk0 -direct=1 -numjobs=1 -thread
> > > > > > -group_reporting -ioengine=psync -iodepth=1 -size=100M
> > > > > > -name=mytest -bs=16k -rw=randwrite
> > > > > > mytest: (g=0): rw=randwrite, bs=(R) 16.0KiB-16.0KiB, (W)
> > > > > > 16.0KiB-16.0KiB, (T) 16.0KiB-16.0KiB, ioengine=psync, iodepth=1
> > > > > > result:
> > > > > > Run status group 0 (all jobs):
> > > > > > WRITE: bw=6499KiB/s (6655kB/s), 6499KiB/s-6499KiB/s
> > > > > > (6655kB/s-6655kB/s), io=100MiB (105MB), run=15756-15756msec
> Disk
> > > > > > stats
> > > > > (read/write):
> > > > > > mmcblk0: ios=51/6347, merge=0/0, ticks=84/15120,
> in_queue=15204,
> > > > > > util=99.80%
> > > > >
> > > > > It looks like the rand-read tests above are degrading with the new
> > > > > changes, while rand-writes are both improving and degrading.
> > > > >
> > > > > To summarize my view from all the tests you have done at this point
> > > > > (thanks a lot); it looks like the block I/O merging isn't really
> > > > > happening at common blocklayer, at least to that extent that would
> > > > > benefit us. Clearly you have shown that by the suggested change in
> > > > > the mmc host driver, by detecting whether the "next" request is
> > > > > sequential to the previous one, which allows us to skip a
> > > > > CMD12 and minimize some command overhead.
> > > > >
> > > > > However, according to the latest tests above, you have also proved
> > > > > that the changes in the mmc host driver doesn't come without a cost.
> > > > > In particular, small random-reads would degrade in performance from
> > > > > these changes.
> > > > >
> > > > > That said, it looks to me that rather than trying to improve things
> > > > > for one specific mmc host driver, it would be better to look at this
> > > > > from the generic block layer point of view - and investigate why
> > > > > sequential reads/writes aren't getting merged often enough for the
> > > > > MMC/SD case. If we can fix the problem there, all mmc host drivers
> would
> > > benefit I assume.
> > > > >
> > > >
> > > > So you are thinking about how to patch this in MMC/SD?
> > > > I don't know if this method is compatible with other MMC Hosts? Or
> > > > they need to patch other code on their host driver
> > >
> > > I would not limit this to the core layer of MMC/SD. The point I was trying to
> > > make was that it doesn't look like the generic block layer is merging the
> > > sequential I/O requests in the most efficient way, at least for the eMMC/SD
> > > devices. Why this is the case, I can't tell. It looks like we need to do some
> more
> > > in-depth analysis to understand why merging isn't efficient for us.
> > >
> > > >
> > > > > BTW, have you tried with different I/O schedulers? If you haven't
> > > > > tried BFQ, I suggest you do as it's a good fit for MMC/SD.
> > > > >
> > > >
> > > > I don’t know what is different I/O schedulers means?
> > >
> > > What I/O scheduler did you use when running the test?
> > >
> > > For MMC/SD the only one that makes sense to use is BFQ, however that
> needs
> > > to be configured via sysfs after boot. There is no way, currently, to make it
> the
> > > default, I think. You may look at Documentation/block/bfq-iosched.rst, if
> you
> > > are more interested.
> > >
> > > Kind regards
> > > Uffe
> > > ------Please consider the environment before printing this e-mail.
> >