[Xen-devel] [PATCH 2/2] blkback: Add default policy values for I/O QoS code

[William Pitcock <nenolod@xxxxxxxxxxxxxxxx>]

This patch adds default values which define a default QoS policy for
guest I/O. A sysctl interface will be added once /proc/sys/xen is available
again... unless I come up with a better idea in the meantime.

Ideas?

Signed-off-by: William Pitcock <nenolod@xxxxxxxxxxxxxxxx>
---
 drivers/xen/blkback/interface.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/drivers/xen/blkback/interface.c b/drivers/xen/blkback/interface.c
index c6c3e14..9541ec4 100644
--- a/drivers/xen/blkback/interface.c
+++ b/drivers/xen/blkback/interface.c
@@ -34,9 +34,13 @@
 #include <xen/events.h>
 #include <xen/grant_table.h>
 #include <linux/kthread.h>
+#include <linux/sysctl.h>
 
 static struct kmem_cache *blkif_cachep;
 
+static int blkif_reqmax = 500000;
+static int blkif_reqrate = 512;
+
 blkif_t *blkif_alloc(domid_t domid)
 {
        blkif_t *blkif;
@@ -53,6 +57,11 @@ blkif_t *blkif_alloc(domid_t domid)
        blkif->st_print = jiffies;
        init_waitqueue_head(&blkif->waiting_to_free);
 
+       /* initialize QoS values to defaults */
+       blkif->reqrate = blkif_reqrate;
+       blkif->reqmax = blkif_reqmax;
+       blkif->reqcount = blkif->reqmax;
+
        return blkif;
 }
 
-- 
1.6.1.3


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