> > > Hi, > > > > This is Sreenivasa from Honeywell. I am currently working on RTOE and have > > to do the performance test of RTOE. That is, the time needed for each API > > calls. Since the time taken for the execution of the APIs are in > > micro/nano seconds, I need functions in C which gives time in Micro or > > nano seconds. But there is no such functions in C which gives time in > > micro or nano seconds.
Most hardware platforms can't give you times in nanoseconds any way - at best you can expect time precission in the range of one microsecond - even if the TSC may have a resolution of 32ns the reading of the timer takes some time so the timesatmp is only exact to at best 1 microsecond. And also if we go for software time functions, they > > themselves take some time to execute. So we are planning to go for using > > internal counters provided by the system. I came to know that you also > > worked on similar lines by visiting the following site: > > http://www.realtimelinux.org/archives/realtime/20007/0010.html Is there > > any way to access the internal counters? And if so, can you please help me > > regarding this. > You can read the TSC on X86 (you did not specify which arch you are talking about so I'll assume X86...) with the rdtsc assembly instruction (if the board has a TSC). If you are on a system with a 8254 you are in trouble if you need nano second resolution (one tick on the 8254 is 838ns but you need a few cycles to read it so you will probably get no better than 10us time stamp resolution). __inline__ unsigned long long int hwtime(void) { unsigned long long int x; __asm__("rdtsc\n\t" :"=A" (x)); return x; } hofrat -- [rtl] --- To unsubscribe: echo "unsubscribe rtl" | mail [EMAIL PROTECTED] OR echo "unsubscribe rtl <Your_email>" | mail [EMAIL PROTECTED] -- For more information on Real-Time Linux see: http://www.rtlinux.org/
