RDTSC use in C: Post: 302237580

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Top Forums Programming RDTSC use in C: Post 302237580 by GloriousDaisy on Thursday 18th of September 2008 12:58:16 AM

09-18-2008

Registered User

RDTSC use in C:

I have to use rdtsc on ubuntu for performance evaluation. But i am not getting the correct value. I am placing a sleep on 10 seconds, but value i get is some 1 sec... i dont know where im going wrong?

Code:

#include<sys/time.h>
#include<time.h>
#include<stdio.h>
typedef unsigned long long ticks;

static __inline__ ticks getticks(void)
{
     unsigned a, d;
     asm("cpuid");
     asm volatile("rdtsc" : "=a" (a), "=d" (d));

     return (((ticks)a) | (((ticks)d) << 32));
}
int main(){
     int r = 0;
     ticks tick,tick1,tickh;
     unsigned time =0;

     tick = getticks();
   
     sleep(10);
   
     tick1 = getticks();
   
     time = (unsigned)((tick1-tick)/1662543);
    printf("\ntime in MS%u\n",time);
return 0;
}

cat /proc/cpuinfo gives

Code:

pprocessor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 14
model name      : Genuine Intel(R) CPU           T2300  @ 1.66GHz
stepping        : 8
cpu MHz         : 1662.543
cache size      : 2048 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 10
wp              : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 ss tm pbe constant_tsc up arch_perfmon bts pni monitor vmx est tm2 xtpr
bogomips        : 3328.87
clflush size    : 64

Last edited by vino; 09-18-2008 at 03:45 AM.. Reason: added code tags

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what-patch

WHAT-PATCH(1)                                                 General Commands Manual                                                WHAT-PATCH(1)

NAME

       what-patch - detect which patch system a Debian package uses

SYNOPSIS

       what-patch [options]

DESCRIPTION

       what-patch examines the debian/rules file to determine which patch system the Debian package is using.

       what-patch should be run from the root directory of the Debian source package.

OPTIONS

       Listed below are the command line options for what-patch:

       -h, --help
              Display a help message and exit.

       -v     Enable verbose mode.  This will include the listing of any files modified outside or the debian/ directory and report any additional
              details about the patch system if available.

AUTHORS

       what-patch was written by Kees Cook <kees@ubuntu.com>, Siegfried-A. Gevatter <rainct@ubuntu.com>, and  Daniel  Hahler  <ubuntu@thequod.de>,
       among others.  This manual page was written by Jonathan Patrick Davies <jpds@ubuntu.com>.

       Both are released under the GNU General Public License, version 3 or later.

SEE ALSO

       The Ubuntu MOTU team has some documentation about patch systems at the Ubuntu wiki: https://wiki.ubuntu.com/PackagingGuide/PatchSystems

       cdbs-edit-patch(1), dbs-edit-patch(1), dpatch-edit-patch(1)

DEBIAN                                                           Debian Utilities                                                    WHAT-PATCH(1)