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List:       linaro-flashbench-results
Subject:    [Flashbench] flashbench sandisk 4GB class4
From:       peter () endian ! com (Peter Warasin)
Date:       2011-07-12 13:11:25
Message-ID: 4E1C47FD.90200 () endian ! com
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Hi

On 11/07/11 22:07, Arnd Bergmann wrote:
> From these numbers, it's definitely clear that there is no factor 3 in it,
> the erase block size has to be either 4MB or 8MB.

great.


> Since you asked about the alignment in the other thread: What is the alignment
> of this partition? Do the numbers change if you align the block to an odd
> number of 4MB blocks (counting from the start of the card)?

This card is aligned to 4MB blocks (the other card was not)


> Still, this could be anything. Bonnie is a high-level benchmark, so
> this could all just mean that MacOS is doing internal write-caching
> for SD cards while Linux does less of that.
> 
> What would be really interesting is to use flashbench on macos, if
> you can get that to build and macos supports O_DIRECT.

we will try that.


> Ok. The numbers I'm usually interested in are:
> 
> * erase block size (smaller is better, lower than 4MB is hard to
>   find on 4GB+ cards)

ok, using -a and so on


> The very easy smoke test is
> 
> flashbench --open-au --open-au-nr=5 --blocksize=2048 --random

> Look at how the numbers go down. Ideally, they should stay at multiple MB/s
> all the way down to the 16KB row, or lower. If they behave like the Kingston
> card you tested earlier, they are completely useless for Linux.


ok, prepare for a bunch of results :)



peter

-- 
:: e n d i a n
:: open source - open minds

:: peter warasin
:: http://www.endian.com   :: peter at endian.com


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