There is a util on our ftp site, ftp://ftp.embeddedARM.com/sdctl that
can run raw write and read speed tests. This util does not use the
Linux driver but manipulates the SD registers directly. Currently, the
only documentation I have on this tool is whats reported with --help.
Anyway, the raw speed of a 256MB UltraII Sandisk SD card on the TS SD
core is listed below: (numbers below are without using DMA)
Sequential read/write speed, 512 byte transfers:
# ./sdctl --writetest --readtest
writetest_kbps=1779
writetest_xfrps=3558
readtest_kbps=1582
readtest_xfrps=3164
Random sector read/write speed, 512 byte transfers:
# ./sdctl --writetest --readtest --random 0x1234
writetest_kbps=23
writetest_xfrps=46
readtest_kbps=661
readtest_xfrps=1322
As you can see, the random sector write speed is horrible
(23kbyte/sec) on SD. Filesystems like EXT3 and EXT2 mounted sync will
probably have worse write speeds due to the number of write "seeks" for
updating the journal and other filesystem metadata (inodes, indirect
blocks, free blk table, etc).
//Jesse Off
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