[Yaffs] [Yaffs-archive] RE: about YAFFS performance

["Yang , Frankie [楊御風]"]

Hi Charles,
I write a test program to read nand device through mtd char device. And the read speed rate is 8M/sec. This means the nand driver's read speed rate is 8M/sec without YAFFS. But mount yaffs on /dev/mtdblock/0, the read speed rate just 1.2M/sec.
Then, I enable CONFIG_YAFFS_USE_GENERIC_RW. This allows YAFFS to use the Linux page cache. The read speed rate is still 1.2M/sec. Now, I change the PAGE_CACHE_SHIFT to 10 and the the PAGE_CACHE_SIZE is 1024 (the original PAGE_CACHE_SHIFT is 12 and PAGE_CACHE_SIZE is 4096), the read speed rate increase to 3.6M/sec, but the data can't pass md5sum check.( I verify whether the data is correct or not but md5sum in busybox).
About this test result, what's your comment? How do you evaluate YAFFS performance?? 
Thanks in advance !!

-----Original Message-----
From: Charles Manning [mailto:manningc2@actrix.gen.nz] 
Sent: Saturday, September 20, 2003 8:55 AM
To: Yang , Frankie [楊御風]; yaffs@toby-churchill.org
Subject: Re: about YAFFS performance

Hello

I was away for a few days so I did not respond to your earlier email.

The overheads in YAFFS associated with reading are very low and performance 
is mainly tied in with reading NAND and verifying. Thus performance is very 
much dependent on various hardware issues, most important are:
* Transfer speed (dependent on the chip select etc timing).
* What verification and ECC you have enabled (and how fasr the CPU can crank 
the data).

I would suggest you first check the read cycle timing on your NAND device. 
Most NAND can cycle in 50nS.

You might also want to enable  CONFIG_YAFFS_USE_GENERIC_RW. This allows YAFFS 
to use the Linux page cache.

-- CHarles


On Wednesday 17 September 2003 18:37, frankie-yang wrote:
> Hi lists,
>  I am now working MIPS 100MHz CPU on linux 2.4.20 with new mtd and =
YAFFS
> (latest code from CVS) running on real nand(samsung 64M) . While I =
mount
> /dev/mtdblock/0 with YAFFS on /mnt/yaffs and write a program to test =
its
> performance, then the speed rate is not good. The read speed rate just
> 1.1Mbytes per seconds! This is not the same with the documentation
> mentioned on CVS.
>
> Any one can tell me why, or give me any suggestion to improve the
> performance ??? And the speed rate listed on Documentation from CVS is
> tested on what environment ????
>
> Thanks in advance
>
> The config what I set while building YAFFS and MTDs
> #
> # Memory Technology Devices (MTD)
> #
> CONFIG_MTD=y
> # CONFIG_MTD_DEBUG is not set
> CONFIG_MTD_PARTITIONS=y
> # CONFIG_MTD_CONCAT is not set
> # CONFIG_MTD_REDBOOT_PARTS is not set
> # CONFIG_MTD_CMDLINE_PARTS is not set
> CONFIG_MTD_CHAR=y
> CONFIG_MTD_BLOCK=y
> # CONFIG_FTL is not set
> # CONFIG_NFTL is not set
>
> #
> # YAFFS
> #
> CONFIG_YAFFS_FS=y
> CONFIG_YAFFS_USE_OLD_MTD=y
> CONFIG_YAFFS_MTD_ENABLED=y
> # CONFIG_YAFFS_USE_NANDECC is not set
> # CONFIG_YAFFS_USE_GENERIC_RW is not set
> CONFIG_YAFFS_DISABLE_WRITE_VERIFY=y
>
>
> =
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