Hi all. I am still in search of a way to allow RTLinx to run a
program to completion without giving the Linux thread and assoc.
user-level apps a slice of either CPU on an SMP box.
I am hearing that certain hardware devices have their operation
tied to recv'ing a while timed jiffie or other interrupt. Thus, Linux may
not be very well behaved if it misses several 1000 or even 1,000,000s of
jiffies -- thus, when the RTL program completes, Linux may not come back
in a stable state. Could someone help me understand these issues. I do
realize that I will need to mlock all the RTLinux application memory so
that there are not application memory pages on disk that need to be
swapped in -- w/o linux runnning the swap will never happen and the system
will lock up -- I think :-).
I do point out that my SMP box is stand alone and contains
reasonable hardware devices (i.e., intel eepr 100 nic, NCR SCSI controller
and WD 9 GB SCSI hard drive, SCSI CD-ROM), so it seems that I should not
cause Linux that much grief by effectively turing off jiffies...
Any insights to the above would be most appreciated.
Thanks!,
Chris
On Tue, 9 Jan 2001, Christopher D. Carothers wrote:
> Hi all. Below is my hacked up version of reserve_cpu.c from
> examples/misc. I am running rtl-3.0-pre10 with Linux 2.4.0-test1. I have a
> dual P-II, 400 Mhz, Micron system (nightshade motherboard). However, when
> I run the code below my system hangs -- this happens even if I just
> allocate a single CPU.
>
> My overall goal is effectively allocate all CPUs -- meaning all
> threads are NOT periodic, thus RTLinux is not giving up a single CPU cycle
> to Linux -- is such a thing possible? I have head this causing problems,
> but I do not quite understand why on a stand alone system (i.e., no NFS or
> other multimedia device are running -- just a hard disk, ram, CPU and
> console -- that is all I need) -- I would of course like Linux to come
> back once my multithreaded program is complete.
>
> Any help would be most appreciated.
>
> Thanks,
> Chris
>
> --------------------------------------------------------------------
> Christopher D. Carothers
>
> Assistant Professor
> Department of Computer Science
> Rensselaer Polytechnic Institute
> 110 8th Street
> Troy, New York 12180-3590
>
> e-mail: [EMAIL PROTECTED]
> web page: www.cs.rpi.edu/~chrisc
> phone: (518) 276-2930
> fax: (518) 276-4033
> --------------------------------------------------------------------
>
> #include <rtl.h>
> #include <pthread.h>
>
> #include <rtl_conf.h>
> #ifndef CONFIG_RTL_SUSPEND_LINUX
> #error CONFIG_RTL_SUSPEND_LINUX not enabled
> #endif
>
> pthread_t thread;
> #define NUMBER_OF_WAITS 10000
> #define NUMBER_OF_OUTER_ITERATIONS 500
> #define NUMBER_OF_INNER_ITERATIONS 10000
>
> volatile int start0=0;
> volatile int start1=0;
>
> void * start_routine(void *arg)
> {
> int i,j;
> hrtime_t start;
>
> rtl_printf("RTL Reserve_cpu thread starts on cpu %d\n",
> hw_smp_processor_id());
>
> if( hw_smp_processor_id() == 0 )
> start0 = 1;
> else if( hw_smp_processor_id() == 1 )
> start1 = 1;
> else
> {
> rtl_printf("RTL error: invalid cpu id %d\n", hw_smp_processor_id());
> return 0;
> }
>
> // i = 0;
> // while( start0 == 0 && start1 == 0 )
> // i++;
>
> rtl_printf("start RTLinux reserve_cpu demo: numcpus=%d\n",
> smp_num_cpus);
>
> for(j=0; j < NUMBER_OF_OUTER_ITERATIONS; j++)
> {
> for(i=0; i < NUMBER_OF_INNER_ITERATIONS; i++)
> {
> start = gethrtime();
> while( gethrtime() - start < 50000 )
> start++;
> }
> rtl_printf("RESERVE Demo: itr = %d, cpu = %d ",j, hw_smp_processor_id());
> }
> rtl_printf("RTLinux RESERVE DEMO: end numcpus=%d\n",smp_num_cpus);
> return 0;
> }
>
> int init_module(void)
> {
> pthread_attr_t attr;
>
> pthread_attr_init (&attr);
> pthread_attr_setcpu_np(&attr, 1);
> pthread_create (&thread, &attr, start_routine, 0);
> // pthread_attr_setcpu_np(&attr, 0);
> // return pthread_create (&thread, &attr, start_routine, 0);
> return 0;
> }
>
> void cleanup_module(void)
> {
> rtl_printf("RTLinux RESERVE DEMO: cleanup numcpus=%d\n",smp_num_cpus);
> }
>
>
>
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