Are you running a SMP system (>1 CPU or core)? Pidin info output will
confirm.
Andy

On 11-09-28 3:24 PM, "Rohit Nair" <community-noreply@qnx.com> wrote:

>Hello,
>
>I am seeing some weird behavior when I run ClockCycles tightly in a loop.
>ClockCycles should always return increasing values, but sometimes it
>returns a value that's less than the previously returned value.
>
>For example - 
>
>	ThreadCtl(_NTO_TCTL_RUNMASK,(int*) 0x1);
>	perror(NULL);
>
>	start = ClockCycles();
>	while(1)
>	{
>		stop = ClockCycles();
>
>		if(start > stop)
>		{
>			diff = start - stop;
>			printf("??? start-%llu, stop-%llu,diff-%llu, iteration -
>%d\n",start,stop,diff,iter);
>			break;
>		}
>		start = stop;
>		iter++;
>	}
>
>
>The iteration at which it happens is widely random. Ranging from 50 to
>30000. 
>
>Could this be because of a wrong setup in init_qtime.c inside startup
>code ? 
>
>
>
>
>_______________________________________________
>
>OSTech
>http://community.qnx.com/sf/go/post89124
>

What cpu/board is this running on?

Rohit Nair wrote:
> Hello,
> 
> I am seeing some weird behavior when I run ClockCycles tightly in a loop. ClockCycles should always return increasing 
values, but sometimes it returns a value that's less than the previously returned value.
> 
> For example - 
> 
> 	ThreadCtl(_NTO_TCTL_RUNMASK,(int*) 0x1);
> 	perror(NULL);
> 
> 	start = ClockCycles();
> 	while(1)
> 	{
> 		stop = ClockCycles();
> 
> 		if(start > stop)
> 		{
> 			diff = start - stop;
> 			printf("??? start-%llu, stop-%llu,diff-%llu, iteration - %d\n",start,stop,diff,iter);
> 			break;
> 		}
> 		start = stop;
> 		iter++;
> 	}
> 
> 
> The iteration at which it happens is widely random. Ranging from 50 to 30000. 
> 
> Could this be because of a wrong setup in init_qtime.c inside startup code ? 
> 
> 
> 
> 
> _______________________________________________
> 
> OSTech
> http://community.qnx.com/sf/go/post89124
> 

Either you have 2 or more processors or it just simply wrapping (3 minutes wrapping time on mips)

On 09/28/2011 03:24 PM, Rohit Nair wrote:
> Hello,
> 
> I am seeing some weird behavior when I run ClockCycles tightly in a loop. ClockCycles should always return increasing 
values, but sometimes it returns a value that's less than the previously returned value.
> 
> For example - 
> 
> 	ThreadCtl(_NTO_TCTL_RUNMASK,(int*) 0x1);
> 	perror(NULL);
> 
> 	start = ClockCycles();
> 	while(1)
> 	{
> 		stop = ClockCycles();
> 
> 		if(start > stop)
> 		{
> 			diff = start - stop;
> 			printf("??? start-%llu, stop-%llu,diff-%llu, iteration - %d\n",start,stop,diff,iter);
> 			break;
> 		}
> 		start = stop;
> 		iter++;
> 	}
> 
> 
> The iteration at which it happens is widely random. Ranging from 50 to 30000. 
> 
> Could this be because of a wrong setup in init_qtime.c inside startup code ? 
> 
> 
> 
> 
> _______________________________________________
> 
> OSTech
> http://community.qnx.com/sf/go/post89124
> 

Of What type are the variables start and stop?

> -----Message d'origine-----
> De : Rohit Nair [mailto:community-noreply@qnx.com]
> Envoyé : 28 septembre 2011 15:24
> À : ostech-core_os
> Objet : ClockCycles Misbehaving
> 
> Hello,
> 
> I am seeing some weird behavior when I run ClockCycles tightly in a loop.
> ClockCycles should always return increasing values, but sometimes it returns
> a value that's less than the previously returned value.
> 
> For example -
> 
> 	ThreadCtl(_NTO_TCTL_RUNMASK,(int*) 0x1);
> 	perror(NULL);
> 
> 	start = ClockCycles();
> 	while(1)
> 	{
> 		stop = ClockCycles();
> 
> 		if(start > stop)
> 		{
> 			diff = start - stop;
> 			printf("??? start-%llu, stop-%llu,diff-%llu, iteration -
> %d\n",start,stop,diff,iter);
> 			break;
> 		}
> 		start = stop;
> 		iter++;
> 	}
> 
> 
> The iteration at which it happens is widely random. Ranging from 50 to
> 30000.
> 
> Could this be because of a wrong setup in init_qtime.c inside startup code ?
> 
> 
> 
> 
> _______________________________________________
> 
> OSTech
> http://community.qnx.com/sf/go/post89124
> 

Hi, 

if this is an ARM CPU, you perhaps have  bug in the timer_value callout.
On ARM ClockCycles is emulated by the kernel.

We had the same issue on an at91sam6263 board in march 2010.
We fixed the callout and sent the patch  to the support portal.
It  was tracked under PR#75223. 

-Michael