Does this even run in userspace? When I try something like this (using mfc0) in userspace, I get an illegal instruction exception. Matt -- Matthew D. Dharm Senior Software Designer Momentum Computer Inc. 1815 Aston Ave. Suite 107 (760) 431-8663 X-115 Carlsbad, CA 92008-7310 Momentum Works For You www.momenco.com > -----Original Message----- > From: linux-mips-bounce@linux-mips.org > [mailto:linux-mips-bounce@linux-mips.org]On Behalf Of Zajerko-McKee, > Nick > Sent: Friday, September 13, 2002 9:41 AM > To: 'Gareth'; linux-mips@linux-mips.org > Subject: RE: Cycle counter > > > Is this under a OS or a single execution? Are there > interrupts enabled? If > so, disable them for measurements. (Clock interrupt, serial > port, etc.). > > BTW, most MIPS implementations for OS's and monitors use > the count/compare > for their main tick. If you set it to zero you may be > stepping on someone's > tick. A better method might be to read the count register > and read it again > at the end and do a difference - that way you preserve > other's values. > > Other reasons for a delay: to fetch code (external mem > ->cache -> cpu) and > push items onto/off the stack... Theres probably more that > I can't think of > right now... > > -----Original Message----- > From: Gareth [mailto:g.c.bransby-99@student.lboro.ac.uk] > Sent: Friday, September 13, 2002 12:28 PM > To: linux-mips@linux-mips.org > Subject: Cycle counter > > > Hi, > > Another question reagarding the mips malta board. I am > wanting to be able to > find out how many cycles a certain loop takes to execute. I > understand there > is > a cycle counter built into the processor that I want to use > for this. I have > a > bit of inline assembly to do the job but the results I am > getting are not > consistent so i think there is probably something wrong > with my attempt at > the > inline assembly. Here is the code : > > void al_signal_start(void); > size_t al_signal_finished(void); > unsigned int GetcpuCycles(void); > > char str[8]; > > int main (void) > { > double x; > al_signal_start(); > > x = al_signal_finished(); > printf("GetcpuCycles says : %f \n",x); > > return 0; > } > > size_t al_signal_finished(void) > { > return GetcpuCycles(); > } > > void al_signal_start(void) > { > int zero,temp; > __asm__("move $2, $zero"); > __asm__("nop"); > __asm__("mtc0 $2, $9" : : "r" (temp)); > __asm__("nop"); > __asm__("nop"); > __asm__("nop"); > } > > unsigned int GetcpuCycles(void) > { > int temp; > __asm__(".set reorder"); > __asm__("mfc0 $2, $9" : : "r" (temp)); > __asm__("nop"); > __asm__("nop"); > __asm__("nop"); > /*__asm__("jr $31" );*/ > } > > > As you can see, main just starts and stops the counter with > no instructions > in > between. I expexcted the cycle count to be zero or close to > it because of > the > instructions required to get the count but this is not the > case. I am > getting > numbers like 8499. Is there just something wrong with my > assembly or is > there > something else I am missing? > > Thanks for any help > Gareth > >
