From owner-svn-src-all@FreeBSD.ORG  Fri Jan 20 22:04:59 2012
Return-Path: <owner-svn-src-all@FreeBSD.ORG>
Delivered-To: svn-src-all@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id A837E106564A;
	Fri, 20 Jan 2012 22:04:59 +0000 (UTC) (envelope-from pjd@FreeBSD.org)
Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:4f8:fff6::2c])
	by mx1.freebsd.org (Postfix) with ESMTP id 9687C8FC14;
	Fri, 20 Jan 2012 22:04:59 +0000 (UTC)
Received: from svn.freebsd.org (localhost [127.0.0.1])
	by svn.freebsd.org (8.14.4/8.14.4) with ESMTP id q0KM4xhM060704;
	Fri, 20 Jan 2012 22:04:59 GMT (envelope-from pjd@svn.freebsd.org)
Received: (from pjd@localhost)
	by svn.freebsd.org (8.14.4/8.14.4/Submit) id q0KM4xTN060702;
	Fri, 20 Jan 2012 22:04:59 GMT (envelope-from pjd@svn.freebsd.org)
Message-Id: <201201202204.q0KM4xTN060702@svn.freebsd.org>
From: Pawel Jakub Dawidek <pjd@FreeBSD.org>
Date: Fri, 20 Jan 2012 22:04:59 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
	svn-src-head@freebsd.org
X-SVN-Group: head
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Cc: 
Subject: svn commit: r230397 -
	head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs
X-BeenThere: svn-src-all@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: "SVN commit messages for the entire src tree \(except for &quot;
	user&quot; and &quot; projects&quot; \)" <svn-src-all.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-all>,
	<mailto:svn-src-all-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-all>
List-Post: <mailto:svn-src-all@freebsd.org>
List-Help: <mailto:svn-src-all-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-all>,
	<mailto:svn-src-all-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 20 Jan 2012 22:04:59 -0000

Author: pjd
Date: Fri Jan 20 22:04:59 2012
New Revision: 230397
URL: http://svn.freebsd.org/changeset/base/230397

Log:
  By default turn off prefetch when listing snapshots.
  In my tests it makes listing snapshots 19% faster with cold cache and
  47% faster with warm cache.
  
  MFC after:	1 week

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

Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.c	Fri Jan 20 21:49:56 2012	(r230396)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ioctl.c	Fri Jan 20 22:04:59 2012	(r230397)
@@ -81,6 +81,12 @@
 
 CTASSERT(sizeof(zfs_cmd_t) < IOCPARM_MAX);
 
+static int snapshot_list_prefetch;
+SYSCTL_DECL(_vfs_zfs);
+TUNABLE_INT("vfs.zfs.snapshot_list_prefetch", &snapshot_list_prefetch);
+SYSCTL_INT(_vfs_zfs, OID_AUTO, snapshot_list_prefetch, CTLFLAG_RW,
+    &snapshot_list_prefetch, 0, "Prefetch data when listing snapshots");
+
 static struct cdev *zfsdev;
 
 extern void zfs_init(void);
@@ -2044,7 +2050,7 @@ zfs_ioc_snapshot_list_next(zfs_cmd_t *zc
 	int error;
 
 top:
-	if (zc->zc_cookie == 0)
+	if (snapshot_list_prefetch && zc->zc_cookie == 0)
 		(void) dmu_objset_find(zc->zc_name, dmu_objset_prefetch,
 		    NULL, DS_FIND_SNAPSHOTS);