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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seeded-in-ubuntu(1)					      General Commands Manual					       seeded-in-ubuntu(1)

NAME

       seeded-in-ubuntu - Determine whether a package is safe to upload during a freeze

SYNOPSIS

       seeded-in-ubuntu [options] package...

DESCRIPTION

       Lists all the current daily images containing the specified packages.  Or whether the package is part of the supported seed.

       If it isn't on an image, it should be safe to upload.  During the final freeze, one should avoid packages in the supported seed too.

       An index of the current manifests is downloaded from UbuntuWire.

OPTIONS

       -b, --binary
	      The  packages  specified	are  binary packages.  This is faster than source packages, as otherwise we must query LP to determine the
	      binary packages that every specified source package builds.

       -u URL, --data-url=URL
	      URL for index of seeded packages.  Default: UbuntuWire's service at http://qa.ubuntuwire.org/ubuntu-seeded-packages/seeded.json.gz.

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

EXAMPLES

       All the images that contain unity:

	      seeded-in-ubuntu -b unity

AUTHORS

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       Both are released under the terms of the ISC License.

ubuntu-dev-tools						   December 2011					       seeded-in-ubuntu(1)