Illumos 5138 - add tunable for maximum number of blocks freed in one txg

[mirror_zfs.git] / module / zfs / dsl_scan.c

diff --git a/module/zfs/dsl_scan.c b/module/zfs/dsl_scan.c
index 5546dad5f656aabc24d5ab4c744c56c627d8baa0..eeec76f78733b5dde5246e5061df092f0088d2bb 100644 (file)
--- a/module/zfs/dsl_scan.c
+++ b/module/zfs/dsl_scan.c
@@ -69,6 +69,8 @@ int zfs_no_scrub_io = B_FALSE; /* set to disable scrub i/o */
 int zfs_no_scrub_prefetch = B_FALSE; /* set to disable scrub prefetch */
 enum ddt_class zfs_scrub_ddt_class_max = DDT_CLASS_DUPLICATE;
 int dsl_scan_delay_completion = B_FALSE; /* set to delay scan completion */
+/* max number of blocks to free in a single TXG */
+ulong zfs_free_max_blocks = 100000;
 
 #define        DSL_SCAN_IS_SCRUB_RESILVER(scn) \
        ((scn)->scn_phys.scn_func == POOL_SCAN_SCRUB || \
@@ -1370,6 +1372,9 @@ dsl_scan_free_should_pause(dsl_scan_t *scn)
        if (zfs_recover)
                return (B_FALSE);
 
+       if (scn->scn_visited_this_txg >= zfs_free_max_blocks)
+               return (B_TRUE);
+
        elapsed_nanosecs = gethrtime() - scn->scn_sync_start_time;
        return (elapsed_nanosecs / NANOSEC > zfs_txg_timeout ||
            (NSEC2MSEC(elapsed_nanosecs) > zfs_free_min_time_ms &&
@@ -1868,4 +1873,7 @@ MODULE_PARM_DESC(zfs_no_scrub_io, "Set to disable scrub I/O");
 
 module_param(zfs_no_scrub_prefetch, int, 0644);
 MODULE_PARM_DESC(zfs_no_scrub_prefetch, "Set to disable scrub prefetching");
+
+module_param(zfs_free_max_blocks, ulong, 0644);
+MODULE_PARM_DESC(zfs_free_max_blocks, "Max number of blocks freed in one txg");
 #endif