Robert Collins <[EMAIL PROTECTED]> wrote: > Windows has (offhand) ~ 30 scheduling levels. It has priority classes, > which 'group' processes, and then relative priorities within each > class.IIRC you can check sched,cc via CVS to see the actual mapping I > used, it's not linear as such, but nearly so.
I looked through sched.cc and i see that you use the UNIX priorities -14 to +14 to map them to 15 different windows priorities on a more or less linear scale, like you already said. Now i found these windows priorities defined in winbase.h and i'm a bit confused: #define THREAD_PRIORITY_ABOVE_NORMAL 1 #define THREAD_PRIORITY_BELOW_NORMAL (-1) #define THREAD_PRIORITY_HIGHEST 2 #define THREAD_PRIORITY_IDLE (-15) #define THREAD_PRIORITY_LOWEST (-2) #define THREAD_PRIORITY_NORMAL 0 #define THREAD_PRIORITY_TIME_CRITICAL 15 Where do the -15 and +15 come from and what do they actually map to? Also THREAD_PRIORITY_TIME_CRITICAL is not mapped in sched.cc to any UNIX priority so if an application calls SetPriorityClass(GetCurrentProcess(), REALTIME_PRIORITY_CLASS) SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_TIME_CRITICAL) what happens actually? As you already say in sched.cc: "We don't want process's going realtime" i guess it doesn't run at -20 but some other priority. > those tests show nothing other than the time it takes to push the iso > through to a bitbucket. Unless there is serious other load on the CPU, > the time *should* be constant. I've run the test many times and they all give the same result, switching from nice -0 to nice --1 always gives a horrible delay, the cpu is not doing any other work at all during the test. But this seems to be an application specific problem and we're still investigating this. While i was writing this i had the idea to do the same test with cat instead of mkisofs with a quite interesting result: $ time cat test.iso | nice -1 dd of=/dev/null real 0m7.171s user 0m2.466s sys 0m4.733s $ time cat test.iso | nice -0 dd of=/dev/null real 0m7.205s user 0m2.794s sys 0m4.467s $ time cat test.iso | nice --1 dd of=/dev/null real 1m51.428s user 0m0.107s sys 0m0.015s I've briefly looked through the pre-1.3x sources and i can't find sched.cc there or sth. of the like, how was it handled back then? thomas -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Bug reporting: http://cygwin.com/bugs.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
