Dear all:
i write a simple program as below to count the speed of writing a file
over usb, gettimeofday before writing and gettimeofday when finish
writing. but I found something make me curious.
1. my program is compiled as static and I use open, write instead of
libc function calls.
2. I use the same kernel and usb modules, kernel version is 2.6.31
the only difference is I have 2 rootfs, both of them are
cross-compiled as arm platform.
Here comes the problem.
the speed of the roofs1 I got is 8MB/s but rootfs2 is 1MB/s
my concerns are:
1. my program is build as static, that means the libs in the roofs has
nothing to do with this program.
2. my program is written with file I/O, instead of file operations
supported by c lib, that means I direct calling kernel system call for
writing data. If my assumption above are correct, that seems the
kernel make me slow on rootfs2.
3. in the beginning, I thought there maybe some other program, like
threads, running on rootfs2 which let my speed get slow.
but how could I find them on the taret?
4. if I really want to find out where my
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