Re: FATSystem "BUG"?

A few questions about your configuration:

1) What version of the OS are you using?
2) What kind of device are you performing those measurements on?
3) What are your cache configurations? Are you using diskcache.dll? How big
is the cache?

You can get the cache information from the registry:

HKLM\System\StorageManager\FATFS

Thank You!

--Vadim Yushprakh

"eddie" <eddiehehe@xxxxxxxxxxx> wrote in message
news:%23iAL0NHrGHA.4192@xxxxxxxxxxxxxxxxxxxxxxx
Hi,
I have written some block device drivers, such as CF card, SD card, IDE
disk...There is a common problem.
For example, in CF card driver, I used the stream interface(XXX_init,
XXX_IoControl...). And I called the AdvertiseInterface() function to
declare it's a block device. So with the FAT system, we could see the
mounted disk in "My device" under WinCE. Then I copied files in & out of
the disk to test the W/R speed. I found that the write-in speed is
900KB/s, but the read-out speed is no more than 500KB/s. That's
insufferable.
I wrote an application to test R/W speed of CF card keep away from FAT: I
called CreateFile() to get the handle of the driver, then used
DeviceIocontrol() to write data in and read out. In this case, the Write
speed is 1.1MB/s, and the Read speed is more than 2MB/s.
And the same situation was appeared in SD card. With FAT: Write 1.2MB/s,
Read 500KB/s. Without FAT: Write 1.4MB/s, Read 4.1MB/s.
Even in the Ram Disk driver, the one used memory space as the virtual
storage space, the test result was: With FAT: Write more than 1.5MB/s,
Read 600KB/s. With out FAT: all very fast speed.
So I thought the FAT system may cause the low efficiency of read operation
under WinCE.
Any suggestion is helpful and thankful.



.

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