svn commit: r323797 - head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs

[Andriy Gapon]

Author: avg
Date: Wed Sep 20 08:36:31 2017
New Revision: 323797
URL: https://svnweb.freebsd.org/changeset/base/323797

Log:
  add vfs_zfs.abd_chunk_size tunable
  
  It is reported that the default value of 4KB results in a substantial
  memory use overhead (at least, on some configurations).  Using 1KB seems
  to reduce the overhead significantly.
  
  PR:		222377
  Reported by:	Sean Chittenden <sean at chittenden.org>
  MFC after:	1 week

Modified:
  head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/abd.c

Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/abd.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/abd.c	Wed Sep 20 08:27:21 2017	(r323796)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/abd.c	Wed Sep 20 08:36:31 2017	(r323797)
@@ -150,6 +150,13 @@ boolean_t zfs_abd_scatter_enabled = B_TRUE;
  */
 size_t zfs_abd_chunk_size = 4096;
 
+#if defined(__FreeBSD__) && defined(_KERNEL)
+SYSCTL_DECL(_vfs_zfs);
+
+SYSCTL_ULONG(_vfs_zfs, OID_AUTO, abd_chunk_size, CTLFLAG_RDTUN,
+    &zfs_abd_chunk_size, 0, "The size of the chunks ABD allocates");
+#endif
+
 #ifdef _KERNEL
 extern vmem_t *zio_alloc_arena;
 #endif