linux-kernel - Re: [PATCH] mmc: Added quirks for Ricoh 1180:e823 lower base clock frequency

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Date:	Tue, 12 Jul 2011 12:20:17 -0400
From:	Chris Ball <cjb@...top.org>
To:	Manoj Iyer <manoj.iyer@...onical.com>
Cc:	linux-kernel@...r.kernel.org, jbarnes@...tuousgeek.org,
	matsumur@....ricoh.co.jp, linux-pci@...r.kernel.org,
	linux-mmc@...r.kernel.org
Subject: Re: [PATCH] mmc: Added quirks for Ricoh 1180:e823 lower base clock frequency

Hi Manoj,

On Tue, Jul 12 2011, Manoj Iyer wrote:
> Test System: ThinkPad X220 Tablet, using Sandisk 2GB Class 2 SD, I did
> not see any considerable change in read/write times. Also, tested a
> Transcend MMCPlus 2GB card, before the patch was applied it would not
> mount the card, and would cause IO errors on read/write, but after the
> patch it mounts and works correctly.
> [..]
> ============ BEFORE THE PATCH ===============
> Sandisk 2GB Class2 SD
> =============================================
> === WRITE ===
> u@u:~$ ls -lh test.file
> -rw-r--r-- 1 u u 10M 2011-07-12 10:19 test.file
> u@u:~$ time cp test.file /media/E0FD-1813/copyto
>
> real    0m0.480s
> user    0m0.000s
> sys     0m0.024s
> [..]
> ============ AFTER THE PATCH =============
> Sandisk 2GB Class2 SD
> ==========================================
>
> === WRITE ===
> u@u:~$ time cp ./test.file /media/E0FD-1813/copyto1
>
> real    0m0.757s
> user    0m0.000s
> sys     0m0.044s

This suggests that there *was* a considerable difference in write speed, no?

It might be helpful to use Arnd's flashbench tool¹ for further benchmarking,
since it does the right thing with using direct I/O access without caches.

Thanks,

- Chris.

¹: http://git.linaro.org/gitweb?p=people/arnd/flashbench.git
-- 
Chris Ball   <cjb@...top.org>   <http://printf.net/>
One Laptop Per Child
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