pthread_getaffinity_np issue

Jason Schulz schulz.j at gmail.com
Thu Sep 24 19:11:31 UTC 2015


Hey Konstantin,

Thanks for the quick response.  The version I'm developing with is the latest release.

[jason at fb ~/development/git/uxcn/yafd]$ uname -a
FreeBSD fb 10.2-RELEASE FreeBSD 10.2-RELEASE #0 r286666: Wed Aug 12 15:26:37 UTC 2015     root at releng1.nyi.freebsd.org:/usr/obj/usr/src/sys/GENERIC  amd64

I was able to narrow it down to the following,

#include <stdio.h>

#include <pthread.h>
#include <pthread_np.h>

int main(int argc, char* argv[argc]) {

  long cs = 0;

  pthread_t this = pthread_self();

  cpuset_t cpus;

  CPU_ZERO(&cpus);

  int err = pthread_getaffinity_np(this, sizeof(cpus), &cpus);

  if (err)
    return err;

  cs = (long) CPU_COUNT(&cpus);

  printf("num cpus... %li\n", cs);

  return 0;
}

Compiling with '-D_XOPEN_SOURCE=700',

[jason at fb /tmp]$ clang -D_XOPEN_SOURCE=700 -pthread -o num_cpus num_cpus.c
num_cpus.c:21:15: warning: implicit declaration of function '__bitcountl' is invalid in C99 [-Wimplicit-function-declaration]
  cs = (long) CPU_COUNT(&cpus);
              ^
/usr/include/sys/cpuset.h:63:24: note: expanded from macro 'CPU_COUNT'
#define CPU_COUNT(p)                    BIT_COUNT(CPU_SETSIZE, p)
                                        ^
/usr/include/sys/bitset.h:185:14: note: expanded from macro 'BIT_COUNT'
                __count += __bitcountl((p)->__bits[__i]);               \
                           ^
1 warning generated.
/tmp/num_cpus-560a33.o: In function `main':
num_cpus.c:(.text+0xbd): undefined reference to `__bitcountl'
clang: error: linker command failed with exit code 1 (use -v to see invocation)

However compiling without '-D_XOPEN_SOURCE=700' works,

[jason at fb /tmp]$ clang -pthread -o num_cpus num_cpus.c
[jason at fb /tmp]$

Should I file a bug report?

-J

On Thu, Sep 24, 2015 at 09:32:46PM +0300, Konstantin Belousov wrote:
> On Thu, Sep 24, 2015 at 11:11:27AM -0700, Jason Schulz wrote:
> > I'm having an issue using the non-posix thread affinity methods.  Specifically, I'm having trouble using CPU_COUNT.  I'm trying to use the following code to get the current number of processors in a processes affinity...
> > 
> > 
> > 
> > long cs = 0;
> > 
> > #if defined(HAVE_LINUX) || defined(HAVE_FREEBSD)
> > 
> > pthread_t this = pthread_self();
> > 
> > cpu_set_t cpus;
> > 
> > CPU_ZERO(&cpus);
> > 
> > int err = pthread_getaffinity_np(this, sizeof(cpus), &cpus);
> > 
> > if (err)
> >   return err;
> > 
> > cs = (long) CPU_COUNT(&cpus);
> > 
> > 
> > 
> > However, I get the compiler error...
> > 
> > 
> > 
> > clang -DHAVE_CONFIG_H -I.      -g -O2 -D_THREAD_SAFE -pthread -pipe -std=c99 -D_XOPEN_SOURCE=700 -pedantic -Wall -Wextra -Wsign-conversion -Wconversion -Werror -MT thread.o -MD -MP -MF .deps/thread.Tpo -c -o thread.o thread.c
> > thread.c:85:15: error: implicit declaration of function '__bitcountl' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
> >   cs = (long) CPU_COUNT(&cpus);
> >               ^
> > /usr/include/sys/cpuset.h:63:24: note: expanded from macro 'CPU_COUNT'
> > #define CPU_COUNT(p)                    BIT_COUNT(CPU_SETSIZE, p)
> >                                         ^
> > /usr/include/sys/bitset.h:185:14: note: expanded from macro 'BIT_COUNT'
> >                 __count += __bitcountl((p)->__bits[__i]);               \
> >                            ^
> > 1 error generated.
> > 
> > 
> > 
> > I'm able to use CPU_ISSET to the same effect, but obviously I'd rather use CPU_COUNT.  Suggestions?
> > 
> 
> Show the minimal example demonstrating the issue, specify the version
> of the system and which you use.  My guess is that you did not added
> #include <sys/types.h> before including sys/cpuset.h.


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