On 8/23/2013 8:42 AM, Vanheesbeke Stefaan wrote:
Someone can comment on this? How can I boost performance of the
libftdi 1.0 to come closer to the 0.20 release?
Some benchmarks on the target (1GHZ single core AMD-processor, running
windows XP)
The test is just looping a read call, latency set to 1, so
theoretically, 1000 loops / second should be performed. No data is
transferred.
Written in c and compiled with gcc.
TimerMsec t;
t.Start();
while (1)
{
ret = ftdi_read_data(ftdi2, temp, 1024);
if (ret < 0)
printf("Error reading\n");
loops++;
if (t.Peek() > 1000)
{
t.Start();
printf("%d loops\n", loops);
loops = 0;
}
}
- libftdi 1.0 + WinUSB driver --> ~920 loops/second and > 25% cpu-load
- libftdi 0.20 + libusb-win32 driver --> ~900 loops/second and 6 to 8%
cpu-load.
Same test on my desktop pc does not reveal these differences (multi
core, more cache, modern operating system, ...)
The first thing I would do is recompile with profiling enabled. When you
run the profiled version it will generate a set of data that should give
you some insight to where CPU time is being consumed. You probably have
the profiler already but I've not done this on Windows before.
You need to add the -pg option when compiling to enable the profiler
which will then generate a gmon.out the next time you run the
application. Run gprof as shown below to analyze the profile data and
dump it into a readable text file.
gprof <your app> gmon.out > prof_info.txt
There is a lot more info at:
http://www.thegeekstuff.com/2012/08/gprof-tutorial/
I am very interested in your results seeing as my current project will
be managing upwards of 50 FTDI devices on a single system!
Ryan
--
libftdi - see http://www.intra2net.com/en/developer/libftdi for details.
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