svn commit: r368309 - head/contrib/llvm-project/llvm/lib/Support/Unix

[Dimitry Andric]

Author: dim
Date: Thu Dec  3 19:29:18 2020
New Revision: 368309
URL: https://svnweb.freebsd.org/changeset/base/368309

Log:
  Merge commit d989ffd10 from llvm git (by Dimitry Andric):
  
    Implement computeHostNumHardwareThreads() for FreeBSD
  
    This retrieves CPU affinity via FreeBSD's cpuset(2) API, and makes
    LLVM respect affinity settings configured by the user via the
    cpuset(1) command.
  
    In particular, this allows to reduce the number of threads used on
    machines with high core counts, which can interact badly with
    parallelized build systems. This is particularly noticable with lld,
    which spawns lots of threads even for linking e.g. hello_world!
  
    This fix is related to PR48193, but does not adress the more
    fundamental problem, which is that LLVM by default grabs as many CPUs
    and/or threads as possible.
  
    Reviewed By: MaskRay
  
    Differential Revision: https://reviews.llvm.org/D92271
  
  Originally by:	mjg
  MFC after:	1 week

Modified:
  head/contrib/llvm-project/llvm/lib/Support/Unix/Threading.inc

Modified: head/contrib/llvm-project/llvm/lib/Support/Unix/Threading.inc
==============================================================================
--- head/contrib/llvm-project/llvm/lib/Support/Unix/Threading.inc	Thu Dec  3 19:26:21 2020	(r368308)
+++ head/contrib/llvm-project/llvm/lib/Support/Unix/Threading.inc	Thu Dec  3 19:29:18 2020	(r368309)
@@ -28,6 +28,7 @@
 
 #if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
 #include <errno.h>
+#include <sys/cpuset.h>
 #include <sys/sysctl.h>
 #include <sys/user.h>
 #include <unistd.h>
@@ -282,7 +283,13 @@ SetThreadPriorityResult llvm::set_thread_priority(Thre
 #include <thread>
 
 int computeHostNumHardwareThreads() {
-#ifdef __linux__
+#if defined(__FreeBSD__)
+  cpuset_t mask;
+  CPU_ZERO(&mask);
+  if (cpuset_getaffinity(CPU_LEVEL_WHICH, CPU_WHICH_TID, -1, sizeof(mask),
+                         &mask) == 0)
+    return CPU_COUNT(&mask);
+#elif defined(__linux__)
   cpu_set_t Set;
   if (sched_getaffinity(0, sizeof(Set), &Set) == 0)
     return CPU_COUNT(&Set);