Enable thread affinity for Power

[Hahnfeld]

Summary

To make this work according to the OpenMP spec, the runtime needs
information about the hardware topology. On Linux the default way
is to parse /proc/cpuinfo which contains this information for x86
machines but (at least) not for Power architectures.

Fortunately, there is a different code path which is able to get
that data from sysfs. The needed patch has landed in 2006 for
Linux 2.6.16 which is safe to assume nowadays (even RHEL 5 had
a kernel version derived from 2.6.18, and we are now at RHEL 7!).

[Hahnfeld]

runtime/src/kmp_affinity.cpp

1839 ↗

(On Diff #123944)

I thought about switching the default for x86 as well because virtually every Linux system should support these sysfs nodes nowadays, but in the end decided to keep the current code path...

[Hahnfeld]

Ping

[AndreyChurbanov]

LGTM

Though not tested as I don't have access to power machine...

openmp/trunk/runtime/src/kmp_affinity.cpp

return -1;                                                                 \
         CHECK_LINE;
         char *p = strchr(buf + sizeof(s1) - 1, ':');
         unsigned val;
         if ((p == NULL) || (KMP_SSCANF(p + 1, "%u\n", &val) != 1))
           goto no_val;
         if (threadInfo[num_avail][osIdIndex] != UINT_MAX)
           goto dup_field;
         threadInfo[num_avail][osIdIndex] = val;
-#if KMP_OS_LINUX && USE_SYSFS_INFO
+#if KMP_OS_LINUX && !(KMP_ARCH_X86 || KMP_ARCH_X86_64)
         char path[256];
         KMP_SNPRINTF(
             path, sizeof(path),
             "/sys/devices/system/cpu/cpu%u/topology/physical_package_id",
             threadInfo[num_avail][osIdIndex]);
         __kmp_read_from_file(path, "%u", &threadInfo[num_avail][pkgIdIndex]);
 
         KMP_SNPRINTF(path, sizeof(path),

openmp/trunk/runtime/src/kmp_os.h

 #define KMP_COMPILER_GCC 1
 #elif defined(_MSC_VER)
 #undef KMP_COMPILER_MSVC
 #define KMP_COMPILER_MSVC 1
 #else
 #error Unknown compiler
 #endif
 
-#if (KMP_OS_LINUX || KMP_OS_WINDOWS) && !KMP_OS_CNK && !KMP_ARCH_PPC64
+#if (KMP_OS_LINUX || KMP_OS_WINDOWS) && !KMP_OS_CNK
 #define KMP_AFFINITY_SUPPORTED 1
 #if KMP_OS_WINDOWS && KMP_ARCH_X86_64
 #define KMP_GROUP_AFFINITY 1
 #else
 #define KMP_GROUP_AFFINITY 0
 #endif
 #else
 #define KMP_AFFINITY_SUPPORTED 0

 #endif
 
 // Support of BGET usage
 #ifndef KMP_USE_BGET
 #define KMP_USE_BGET 1
 #endif
 
 // Switches for OSS builds
-#ifndef USE_SYSFS_INFO
-#define USE_SYSFS_INFO 0
-#endif
 #ifndef USE_CMPXCHG_FIX
 #define USE_CMPXCHG_FIX 1
 #endif
 
 // Enable dynamic user lock
 #if OMP_45_ENABLED
 #define KMP_USE_DYNAMIC_LOCK 1
 #endif