[Patch] credit: Update other parameters when setting tslice_ms

[Nathan Studer <nate.studer@dornerworks.com>]

From: Nate Studer <nate.studer@dornerworks.com>

Add a utility function to update the rest of the timeslice
accounting fields when updating the timeslice of the
credit scheduler, so that capped CPUs behave correctly.

Before this patch changing the timeslice to a value higher
than the default would result in a domain not utilizing
its full capacity and changing the timeslice to a value
lower than the default would result in a domain exceeding
its capacity.

Signed-off-by: Nate Studer <nate.studer@dornerworks.com>
---
 xen/common/sched_credit.c |   20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)
 mode change 100644 => 100755 xen/common/sched_credit.c

diff --git a/xen/common/sched_credit.c b/xen/common/sched_credit.c
old mode 100644
new mode 100755
index 28dafcf..db5512e
--- a/xen/common/sched_credit.c
+++ b/xen/common/sched_credit.c
@@ -1071,6 +1071,17 @@ csched_dom_cntl(
     return 0;
 }
 
+static inline void
+__csched_set_tslice(struct csched_private *prv, unsigned timeslice)
+{
+    prv->tslice_ms = timeslice;
+    prv->ticks_per_tslice = CSCHED_TICKS_PER_TSLICE;
+    if ( prv->tslice_ms < prv->ticks_per_tslice )
+        prv->ticks_per_tslice = 1;
+    prv->tick_period_us = prv->tslice_ms * 1000 / prv->ticks_per_tslice;
+    prv->credits_per_tslice = CSCHED_CREDITS_PER_MSEC * prv->tslice_ms;
+}
+
 static int
 csched_sys_cntl(const struct scheduler *ops,
                         struct xen_sysctl_scheduler_op *sc)
@@ -1089,7 +1100,7 @@ csched_sys_cntl(const struct scheduler *ops,
                     || params->ratelimit_us < XEN_SYSCTL_SCHED_RATELIMIT_MIN))
             || MICROSECS(params->ratelimit_us) > MILLISECS(params->tslice_ms) )
                 goto out;
-        prv->tslice_ms = params->tslice_ms;
+        __csched_set_tslice(prv, params->tslice_ms);
         prv->ratelimit_us = params->ratelimit_us;
         /* FALLTHRU */
     case XEN_SYSCTL_SCHEDOP_getinfo:
@@ -1899,12 +1910,7 @@ csched_init(struct scheduler *ops)
         sched_credit_tslice_ms = CSCHED_DEFAULT_TSLICE_MS;
     }
 
-    prv->tslice_ms = sched_credit_tslice_ms;
-    prv->ticks_per_tslice = CSCHED_TICKS_PER_TSLICE;
-    if ( prv->tslice_ms < prv->ticks_per_tslice )
-        prv->ticks_per_tslice = 1;
-    prv->tick_period_us = prv->tslice_ms * 1000 / prv->ticks_per_tslice;
-    prv->credits_per_tslice = CSCHED_CREDITS_PER_MSEC * prv->tslice_ms;
+    __csched_set_tslice(prv, sched_credit_tslice_ms);
 
     if ( MICROSECS(sched_ratelimit_us) > MILLISECS(sched_credit_tslice_ms) )
     {
-- 
1.7.9.5