From 414eb9f6b7338730f7767d92049c96f31a2112b7 Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Mon, 14 Dec 2009 09:36:54 -0200
Subject: [PATCH 1/2] Documentation: Fix description of cache option for drives

RH-Author: Kevin Wolf <kwolf@redhat.com>
Message-id: <1260783414-5455-1-git-send-email-kwolf@redhat.com>
Patchwork-id: 3941
O-Subject: [RHEL-5.5 KVM PATCH] Documentation: Fix description of cache option
	for drives
Bugzilla: 545194
RH-Acked-by: Juan Quintela <quintela@redhat.com>
RH-Acked-by: Markus Armbruster <armbru@redhat.com>
RH-Acked-by: Dor Laor <dlaor@redhat.com>

Bugzilla: 545194
Upstream status: Not applicable

The default for qcow2 is cache=none now.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 qemu/qemu-doc.texi |   10 ++++------
 1 files changed, 4 insertions(+), 6 deletions(-)

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 qemu/qemu-doc.texi |   10 ++++------
 1 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/qemu/qemu-doc.texi b/qemu/qemu-doc.texi
index 3d64f08..fb4da85 100644
--- a/qemu/qemu-doc.texi
+++ b/qemu/qemu-doc.texi
@@ -280,7 +280,7 @@ This option specifies the serial number to assign to the device.
 @var{boot} if "on" enables extboot for a given drive so it can be used as a boot drive.
 @end table
 
-By default, writethrough caching is used for all block device.  This means that
+Writethrough caching means that
 the host page cache will be used to read and write data but write notification
 will be sent to the guest only when the data has been reported as written by
 the storage subsystem.
@@ -295,11 +295,9 @@ The host page can be avoided entirely with @option{cache=none}.  This will
 attempt to do disk IO directly to the guests memory.  QEMU may still perform
 an internal copy of the data.
 
-Some block drivers perform badly with @option{cache=writethrough}, most notably,
-qcow2.  If performance is more important than correctness,
-@option{cache=writeback} should be used with qcow2.  By default, if no explicit
-caching is specified for a qcow2 disk image, @option{cache=writeback} will be
-used.  For all other disk types, @option{cache=writethrough} is the default.
+By default, if no explicit caching is specified for a qcow2 disk image,
+@option{cache=none} will be used.  For all other disk types,
+@option{cache=writethrough} is the default.
 
 Instead of @option{-cdrom} you can use:
 @example
-- 
1.6.3.rc4.29.g8146