Date: Thu, 24 Sep 2015 22:26:23 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Jason Schulz <schulz.j@gmail.com> Cc: freebsd-threads@freebsd.org, jhb@freebsd.org Subject: Re: pthread_getaffinity_np issue Message-ID: <20150924192623.GL67105@kib.kiev.ua> In-Reply-To: <20150924191121.GG3104@gmail.com> References: <20150924181127.GC3104@gmail.com> <20150924183246.GK67105@kib.kiev.ua> <20150924191121.GG3104@gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Thu, Sep 24, 2015 at 12:11:21PM -0700, Jason Schulz wrote:
> Hey Konstantin,
>
> Thanks for the quick response. The version I'm developing with is the latest release.
>
> [jason@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@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@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@fb /tmp]$ clang -pthread -o num_cpus num_cpus.c
> [jason@fb /tmp]$
>
> Should I file a bug report?
So your issue only appears when you specify _XOPEN_SOURCE. This is reasonable,
because __bitcount stuff in sys/types.h was put under _BSD_VISIBLE protection.
I am not sure why and I Cc:ed the author of the change.
IMO all symbols from __bitcount* are in the private namespace and could
be made unconditionally accessible, to avoid surprises. I put the patch
at the end of the message which does this.
That said, pthread_np.h is not specified by POSIX/X/Open, so your use of
the header and affinity functionality is not covered by _XOPEN_SOURCE
contract. The consequences of mixing implementation-specific headers
and request for the standard-compliance can be arbitrary.
>
> -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.
diff --git a/sys/sys/types.h b/sys/sys/types.h
index 4a66a4e..4dfd8ef 100644
--- a/sys/sys/types.h
+++ b/sys/sys/types.h
@@ -290,9 +290,6 @@ typedef _Bool bool;
* The following are all things that really shouldn't exist in this header,
* since its purpose is to provide typedefs, not miscellaneous doodads.
*/
-#if __BSD_VISIBLE
-
-#include <sys/select.h>
#ifdef __POPCNT__
#define __bitcount64(x) __builtin_popcountll((__uint64_t)(x))
@@ -356,6 +353,10 @@ __bitcount64(__uint64_t _x)
#define __bitcount(x) __bitcount32((unsigned int)(x))
#endif
+#if __BSD_VISIBLE
+
+#include <sys/select.h>
+
/*
* minor() gives a cookie instead of an index since we don't want to
* change the meanings of bits 0-15 or waste time and space shifting
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20150924192623.GL67105>