I don't know what you will learn with profiling the loop I showed. This basically runs only the call to the ftdi library around 1000 times/second.
From: Ryan Tennill [mailto:[email protected]] Sent: vrijdag 23 augustus 2013 16:35 To: [email protected] Subject: Re: performance of different versions of libftdi 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. To unsubscribe send a mail to [email protected]<mailto:[email protected]> -- libftdi - see http://www.intra2net.com/en/developer/libftdi for details. To unsubscribe send a mail to [email protected]
