1 files changed, 52 insertions, 0 deletions

diff --git a/include/litmus/affinity.h b/include/litmus/affinity.h
new file mode 100644
index 000000000000..4d7c618c8175
--- /dev/null
+++ b/include/litmus/affinity.h
@@ -0,0 +1,52 @@
+#ifndef __LITMUS_AFFINITY_H
+#define __LITMUS_AFFINITY_H
+
+#include <linux/cpumask.h>
+
+/* Works like:
+void get_nearest_available_cpu(
+        cpu_entry_t **nearest,
+        cpu_entry_t *start,
+        cpu_entry_t *entries,
+        int release_master,
+        cpumask_var_t cpus_to_test)
+
+Set release_master = NO_CPU for no Release Master.
+
+We use a macro here to exploit the fact that C-EDF and G-EDF
+have similar structures for their cpu_entry_t structs, even though
+they do not share a common base-struct.  The macro allows us to
+avoid code duplication.
+
+ */
+#define get_nearest_available_cpu(nearest, start, entries, release_master, cpus_to_test) \
+{ \
+        (nearest) = NULL; \
+        if (!(start)->linked && likely((start)->cpu != (release_master))) { \
+                (nearest) = (start); \
+        } else { \
+                int __cpu; \
+                \
+                /* FIXME: get rid of the iteration with a bitmask + AND */ \
+                for_each_cpu(__cpu, cpus_to_test) { \
+                        if (likely(__cpu != release_master)) { \
+                                cpu_entry_t *__entry = &per_cpu((entries), __cpu); \
+                                if (cpus_share_cache((start)->cpu, __entry->cpu) \
+                                    && !__entry->linked) { \
+                                        (nearest) = __entry; \
+                                        break; \
+                                } \
+                        } \
+                } \
+        } \
+        \
+        if ((nearest)) { \
+                TRACE("P%d is closest available CPU to P%d\n", \
+                                (nearest)->cpu, (start)->cpu); \
+        } else { \
+                TRACE("Could not find an available CPU close to P%d\n", \
+                                (start)->cpu); \
+        } \
+}
+
+#endif