Re: Throughput question with CF/DiskOnChip

From: Michael Schnell (mschnell_at_bschnell_dot_de_at_aol.com)
Date: 01/02/05

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    Date: Sun, 02 Jan 2005 17:16:58 +0100

    > Rather than
    > using files, we simply divided the MMC address space into a number of
    > different areas and treated those to which data was being streamed as
    > ring buffers. The application firmware writes directly to the media
    > and does not go through a filing system.
    >
    > We also wrote a static FAT-16 file system structure onto the media to
    > make it easier for other application to read the data. This is not
    > used by our firmware.
    >

    I did something similar to read and write a PC compatible FC with a
    (non-Linux) embedded system. here we needed a more complex structure, so
    that multiple files and directories were necessary.

    I wrote a driver that can read and write Data in FAT-16 Files, indeed
    using the File allocation table, but not able to write same, so that
    files only can be overwritten, not created, deleted or modified in size.
    So we use standard Windows means to format the FC and create files
    filled with predefined data.

    > A further performance enhancement is to pre-erase a number of blocks
    > ahead of the data to be written. It is also a good idea to have the
    > largest possible RAM memory buffer between the data source and the
    > media.

    On an FC you can't be sure what to write into a file to have the
    internal memory be filled with the "erased" pattern.

    -Michael

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