linux-kernel - Re: [PATCH v5 2/2] mmc: core: Support packed command for eMMC4.5 device

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Message-ID: <CAKLKtzfzs7hxjXjb0rztvmTUjpiEpLHZeeSr5Sc5xxskZ8rYHw@mail.gmail.com>
Date:	Thu, 1 Mar 2012 14:31:13 +0530
From:	Saugata Das <saugata.das@...aro.org>
To:	merez@...eaurora.org
Cc:	Seungwon Jeon <tgih.jun@...sung.com>, linux-mmc@...r.kernel.org,
	Chris Ball <cjb@...top.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 2/2] mmc: core: Support packed command for eMMC4.5 device

On 29 February 2012 23:40,  <merez@...eaurora.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@...sung.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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