@@ -72,6 +72,69 @@ extern void compaction_defer_reset(struct zone *zone, int order,
bool alloc_success);
extern bool compaction_restarting(struct zone *zone, int order);
+/* Compaction has made some progress and retrying makes sense */
+static inline bool compaction_made_progress(enum compact_result result)
+{
+ /*
+ * Even though this might sound confusing this in fact tells us
+ * that the compaction successfully isolated and migrated some
+ * pageblocks.
+ */
+ if (result == COMPACT_PARTIAL)
+ return true;
+
+ return false;
+}
+
+/* Compaction has failed and it doesn't make much sense to keep retrying. */
+static inline bool compaction_failed(enum compact_result result)
+{
+ /* All zones were scanned completely and still not result. */
+ if (result == COMPACT_COMPLETE)
+ return true;
+
+ return false;
+}
+
+/*
+ * Compaction has backed off for some reason. It might be throttling or
+ * lock contention. Retrying is still worthwhile.
+ */
+static inline bool compaction_withdrawn(enum compact_result result)
+{
+ /*
+ * Compaction backed off due to watermark checks for order-0
+ * so the regular reclaim has to try harder and reclaim something.
+ */
+ if (result == COMPACT_SKIPPED)
+ return true;
+
+ /*
+ * If compaction is deferred for high-order allocations, it is
+ * because sync compaction recently failed. If this is the case
+ * and the caller requested a THP allocation, we do not want
+ * to heavily disrupt the system, so we fail the allocation
+ * instead of entering direct reclaim.
+ */
+ if (result == COMPACT_DEFERRED)
+ return true;
+
+ /*
+ * If compaction in async mode encounters contention or blocks higher
+ * priority task we back off early rather than cause stalls.
+ */
+ if (result == COMPACT_CONTENDED)
+ return true;
+
+ /*
+ * Page scanners have met but we haven't scanned full zones so this
+ * is a back off in fact.
+ */
+ if (result == COMPACT_PARTIAL_SKIPPED)
+ return true;
+
+ return false;
+}
#else
static inline enum compact_result try_to_compact_pages(gfp_t gfp_mask,
unsigned int order, int alloc_flags,
@@ -104,6 +167,20 @@ static inline bool compaction_deferred(struct zone *zone, int order)
return true;
}
+static inline bool compaction_made_progress(enum compact_result result)
+{
+ return false;
+}
+
+static inline bool compaction_failed(enum compact_result result)
+{
+ return false;
+}
+
+static inline bool compaction_withdrawn(enum compact_result result)
+{
+ return true;
+}
#endif /* CONFIG_COMPACTION */
#if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)