This is a discussion on ATA write speed - VxWorks ; Hi all, I am testing file write speeds under VxWorks and am getting very poor performance. I am using VxWorks 5.5.1 x86 on a Pentium M 1.1 GHz single board computer (Intel 855GME chipset). The computer has a compact flash ...
I am testing file write speeds under VxWorks and am getting very poor
performance. I am using VxWorks 5.5.1 x86 on a Pentium M 1.1 GHz
single board computer (Intel 855GME chipset). The computer has a
compact flash slot and we are using a 16 GB CF as the only storage.
The SBC documentation claims the CF slot can do "PIO mode 3, 4 with
Bus Mastering up to 14MB/sec" and we are using a Sandisk Extreme III
30 MB/s CF card, so hardware speeds should not be an issue. The CF is
formatted FAT32 all in one partition.
When I time writing a 640x480 pixel PGM file (307,215 bytes), I get an
average write speed of about 2.2 MB/s. This is testing with writing
10 files in succession, so about 3 MB worth. Is there anything I can
do to tweak some settings to squeeze any more disk performance out?
Is it worth looking at using the CF in raw mode (partitioned) rather
than with a file system? What source files might I look at to try to
pinpoint the bottleneck? Any other ideas?
I have done some searching through the group and what I found does not
sound encouraging. This thread:
claims about 4 MB/s write speed using a faster (clock-speed-wise)
processor and a hard disk (with no difference between FAT and raw file
systems). If I could even reliably and consistently get 4 MB/s that
would be an improvement. For this application, I need to be able to
write 640x480 image files at 10 Hz, or about 3.1 MB/s, in addition to
other CPU-intensive processing.