RE: [PATCH v5 2/2] mmc: core: Support packed command for eMMC4.5 device

[Seungwon Jeon <tgih.jun@samsung.com>]

Hi,

Maya Erez <merez@codeaurora.org> wrote:
> > This patch supports packed command of eMMC4.5 device.
> > Several reads(or writes) can be grouped in packed command
> > and all data of the individual commands can be sent in a
> > single transfer on the bus.
> >
> > Signed-off-by: Seungwon Jeon <tgih.jun@samsung.com>
> > ---
> >  drivers/mmc/card/block.c   |  496
> > +++++++++++++++++++++++++++++++++++++++++--
> >  drivers/mmc/card/queue.c   |   48 ++++-
> >  drivers/mmc/card/queue.h   |   13 ++
> >  drivers/mmc/core/mmc_ops.c |    1 +
> >  include/linux/mmc/core.h   |    4 +
> >  5 files changed, 535 insertions(+), 27 deletions(-)
> >
> Hi,
> 
> We ran performance tests on the packed commands patch. We found out that
> enabling the read packing didn't improve the performance in any of the
> scenarios we ran (see the detailed results below).
> Therefore, we suggest to move the read packing code to a different patch
> and approve only the write packing code for now. The read packing adds
> complexity to the code and we don't see a point in adding it while the
> intention is to disable it.
> 
Thank you for test.
What is your test tool?
Is there any improvement point we can discuss for packed read?

Thanks,
Seungwon Jeon.

> Test results:
> 
> Long read operation:
> ----------------------
> no-packing: 39.5 MB/s
> packed commands patch (both READ and WRITE packing are enabled): 39.5 MB/s
> packed commands patch + enabling only READ packing: 39.5 MB/s
> 
> Several parallel read operations (sum of all the read throughputs):
> ---------------------------
> no-packing: 42.6 MB/s
> packed commands patch(both READ and WRITE packing are enabled): 38 MB/s
> packed commands patch + enabling only READ packing: 38.2 MB/s
> 
> Parallel long read and long write operations (read throughput):
> -----------------------------------------------------------------
> no-packing: 23.8 MB/s
> packed commands patch (both READ and WRITE packing are enabled): 12.6 MB/s
> packed commands patch + enabling only READ packing: 12.5 MB/s
> 
> Parallel short read and long write operations (read throughput):
> -----------------------------------------------------------------
> no-packing: 22.9 MB/s
> packed commands patch (both READ and WRITE packing are enabled): 8.4 MB/s
> packed commands patch + enabling only READ packing: 8.6 MB/s
> 
> Several Parallel short read and short write operations (sum of all the
> read throughputs):
> --------------------------------------------------------------------------
> no-packing: 41.6 MB/s
> packed commands patch (both READ and WRITE packing are enabled): 35 MB/s
> packed commands patch + enabling only READ packing: 36 MB/s
> 
> Thanks,
> Maya Erez
> Consultant for Qualcomm Innovation Center, Inc.
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum
> 
> 
> 
> 
> 
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