[libvirt] [PATCH] doc: blkio: add some notification

[Gao feng]

If the I/O elevator of disk is not cfq, the setting
of blkio.weight is ineffective. And the setting up
blkio.weight_device will fail.

Add notification for this situation.

Signed-off-by: Gao feng <gaofeng at cn.fujitsu.com>
---
 docs/formatdomain.html.in | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index 47d91ab..8d048be 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -740,7 +740,8 @@
       <dd> The optional <code>blkiotune</code> element provides the ability
         to tune Blkio cgroup tunable parameters for the domain. If this is
         omitted, it defaults to the OS provided
-        defaults. <span class="since">Since 0.8.8</span></dd>
+        defaults. Notice: blkiotune is effective only when the I/O elevator
+        of disk is cfq. <span class="since">Since 0.8.8</span></dd>
       <dt><code>weight</code></dt>
       <dd> The optional <code>weight</code> element is the overall I/O
         weight of the guest. The value should be in the range [100,
@@ -761,7 +762,8 @@
         mandatory sub-elements, <code>path</code> describing the
         absolute path of the device, and <code>weight</code> giving
         the relative weight of that device, in the range [100,
-        1000].  <span class="since">Since 0.9.8</span></dd>
+        1000]. The setting up device.weight will fail if the I/O elevator
+        of this disk device is not cfq. <span class="since">Since 0.9.8</span></dd>
     </dl>
 
 
-- 
1.8.1.4