X-Git-Url: https://git.camperquake.de/gitweb.cgi?a=blobdiff_plain;f=module%2Fzfs%2Fzio.c;h=fda76123e4927315bd01d2f5cfb0f4278f368ca0;hb=55d85d5a8c45c4559a4a0e675c37b0c3afb19c2f;hp=a721903a37ab875d594f08b770dc91aa73be1aa9;hpb=5853fe790d1df58c5dd85ea52c5e165b6d43013c;p=zfs.git

diff --git a/module/zfs/zio.c b/module/zfs/zio.c
index a721903..fda7612 100644
--- a/module/zfs/zio.c
+++ b/module/zfs/zio.c
@@ -85,6 +85,22 @@ extern vmem_t *zio_alloc_arena;
 extern int zfs_mg_alloc_failures;
 
 /*
+ * The following actions directly effect the spa's sync-to-convergence logic.
+ * The values below define the sync pass when we start performing the action.
+ * Care should be taken when changing these values as they directly impact
+ * spa_sync() performance. Tuning these values may introduce subtle performance
+ * pathologies and should only be done in the context of performance analysis.
+ * These tunables will eventually be removed and replaced with #defines once
+ * enough analysis has been done to determine optimal values.
+ *
+ * The 'zfs_sync_pass_deferred_free' pass must be greater than 1 to ensure that
+ * regular blocks are not deferred.
+ */
+int zfs_sync_pass_deferred_free = 2; /* defer frees starting in this pass */
+int zfs_sync_pass_dont_compress = 5; /* don't compress starting in this pass */
+int zfs_sync_pass_rewrite = 2; /* rewrite new bps starting in this pass */
+
+/*
  * An allocating zio is one that either currently has the DVA allocate
  * stage set or will have it later in its lifetime.
  */
@@ -771,7 +787,7 @@ zio_free_sync(zio_t *pio, spa_t *spa, uint64_t txg, const blkptr_t *bp,
 
 	ASSERT(!BP_IS_HOLE(bp));
 	ASSERT(spa_syncing_txg(spa) == txg);
-	ASSERT(spa_sync_pass(spa) <= SYNC_PASS_DEFERRED_FREE);
+	ASSERT(spa_sync_pass(spa) < zfs_sync_pass_deferred_free);
 
 	zio = zio_create(pio, spa, txg, bp, NULL, BP_GET_PSIZE(bp),
 	    NULL, NULL, ZIO_TYPE_FREE, ZIO_PRIORITY_FREE, flags,
@@ -1068,7 +1084,7 @@ zio_write_bp_init(zio_t *zio)
 		ASSERT(zio->io_child_type == ZIO_CHILD_LOGICAL);
 		ASSERT(!BP_GET_DEDUP(bp));
 
-		if (pass > SYNC_PASS_DONT_COMPRESS)
+		if (pass >= zfs_sync_pass_dont_compress)
 			compress = ZIO_COMPRESS_OFF;
 
 		/* Make sure someone doesn't change their mind on overwrites */
@@ -1097,7 +1113,7 @@ zio_write_bp_init(zio_t *zio)
 	 * There should only be a handful of blocks after pass 1 in any case.
 	 */
 	if (bp->blk_birth == zio->io_txg && BP_GET_PSIZE(bp) == psize &&
-	    pass > SYNC_PASS_REWRITE) {
+	    pass >= zfs_sync_pass_rewrite) {
 		enum zio_stage gang_stages = zio->io_pipeline & ZIO_GANG_STAGES;
 		ASSERT(psize != 0);
 		zio->io_pipeline = ZIO_REWRITE_PIPELINE | gang_stages;