On 00:51, Mon 14 Apr 08, Øyvind Kolås wrote: > One issue in babl's current design is that other activity on the > system at the same time as measuring is performed can skew results > quite a lot for a given conversion, not sure if there is a good way to > deal with this at runtime though. Hi, yes, the gettimeofday function is indeed not the best profiling method. I have put some though into this and came up with several alternatives how to tackle this problem. The first possibility is to replace gettimeofday by system function that accounts only for time of the given process, such as getrusage. Although the getrusage function provides way to measure process time in microseconds, the real resolution is far from 1 microsecond. Using getrusage would mean that the runtime profiling would have to take approx. 100x longer than in the current state to get reasonable results for the fastest conversions. And that is far from ideal. The second possibility is to profile during the compilation, which would allow for much longer and precise profiling. This would generate some profiling data in a form of a C file and would compile into babl in the second compile pass. This might work in a situation when the compiling machine is the target machine, however, the results can be of course skewed while this is not the case. Maybe the biggest drawback would be the fact that this contradicts the dynamic paradigm of the library. The third possibility is again to profile longer using getrusage or similar function, this time once per user. The profiling results would be output e.g. to ~/.babl/prof.data and would be reloaded next time. Once new .so with conversion would be found or new babl version installed, the profiling would be done again. So these are the alternatives I came up with. If you prefer one of these or have a better idea, I can investigate it further. Regards, Jan _______________________________________________ Gegl-developer mailing list Gegl-developer@xxxxxxxxxxxxxxxxxxxxxx https://lists.XCF.Berkeley.EDU/mailman/listinfo/gegl-developer
