1 files changed, 30 insertions, 0 deletions
diff --git a/libbcache/movinggc.h b/libbcache/movinggc.h
new file mode 100644
index 0000000..5f15308
--- /dev/null
+++ b/libbcache/movinggc.h
@@ -0,0 +1,30 @@
+#ifndef _BCACHE_MOVINGGC_H
+#define _BCACHE_MOVINGGC_H
+
+/*
+ * We can't use the entire copygc reserve in one iteration of copygc: we may
+ * need the buckets we're freeing up to go back into the copygc reserve to make
+ * forward progress, but if the copygc reserve is full they'll be available for
+ * any allocation - and it's possible that in a given iteration, we free up most
+ * of the buckets we're going to free before we allocate most of the buckets
+ * we're going to allocate.
+ *
+ * If we only use half of the reserve per iteration, then in steady state we'll
+ * always have room in the reserve for the buckets we're going to need in the
+ * next iteration:
+ */
+#define COPYGC_BUCKETS_PER_ITER(ca)					\
+	((ca)->free[RESERVE_MOVINGGC].size / 2)
+
+/*
+ * Max sectors to move per iteration: Have to take into account internal
+ * fragmentation from the multiple write points for each generation:
+ */
+#define COPYGC_SECTORS_PER_ITER(ca)					\
+	((ca)->mi.bucket_size *	COPYGC_BUCKETS_PER_ITER(ca))
+
+void bch_moving_init_cache(struct cache *);
+void bch_moving_gc_stop(struct cache *);
+int bch_moving_gc_thread_start(struct cache *);
+
+#endif