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    SubjectRe: [PATCH v5 2/2] mmc: core: Support packed command for eMMC4.5 device
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    On 29 February 2012 23:40,  <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.

    Have you seen improvement in the write packing ?


    >
    > 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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