Fix hwloc topology traversal code unable to handle situation where L2 cache is common for the packages
Currently cores within package that share the same L2 cache are grouped together.
The current logic behind this assumes that the L2 cache is always at deeper
(or the same) level than the package itself. In case when L2 cache is common
for all packages (and the packages are at deeper level than L2 cache) the whole of
the further topology discovery fails to find any computational units resulting in
following assertion:
Assertion failure at kmp_affinity.cpp(715): nActiveThreads == __kmp_avail_proc.
OMP: Error #13: Assertion failure at kmp_affinity.cpp(715).
This patch adds a bit of a logic that prevents such situation from occurring.
Differential Revision: https://reviews.llvm.org/D61796
git-svn-id: https://llvm.org/svn/llvm-project/openmp/trunk@360890 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/runtime/src/kmp_affinity.cpp b/runtime/src/kmp_affinity.cpp
index 9d08254..b8d585c 100644
--- a/runtime/src/kmp_affinity.cpp
+++ b/runtime/src/kmp_affinity.cpp
@@ -530,7 +530,7 @@
static int __kmp_hwloc_check_numa() {
hwloc_topology_t &tp = __kmp_hwloc_topology;
hwloc_obj_t hT, hC, hL, hN, hS; // hwloc objects (pointers to)
- int depth;
+ int depth, l2cache_depth, package_depth;
// Get some PU
hT = hwloc_get_obj_by_type(tp, HWLOC_OBJ_PU, 0);
@@ -548,8 +548,10 @@
}
}
+ package_depth = hwloc_get_type_depth(tp, HWLOC_OBJ_PACKAGE);
+ l2cache_depth = hwloc_get_cache_type_depth(tp, 2, HWLOC_OBJ_CACHE_UNIFIED);
// check tile, get object by depth because of multiple caches possible
- depth = hwloc_get_cache_type_depth(tp, 2, HWLOC_OBJ_CACHE_UNIFIED);
+ depth = (l2cache_depth < package_depth) ? package_depth : l2cache_depth;
hL = hwloc_get_ancestor_obj_by_depth(tp, depth, hT);
hC = NULL; // not used, but reset it here just in case
if (hL != NULL &&
