[Patch] credit: Update other parameters when setting tslice_ms

[Patch] credit: Update other parameters when setting tslice_ms

[Nathan Studer]

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

Re: [Patch] credit: Update other parameters when setting tslice_ms

[Nate Studer]

CC'ing Dario, so that he has a message to reply to.

On 11/13/2013 4:49 PM, Nathan Studer wrote:
> 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) )
>      {
> 

Re: [Patch] credit: Update other parameters when setting tslice_ms

[George Dunlap]

On 13/11/13 21:49, Nathan Studer wrote:
> 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>

Reviewed-by: George Dunlap <george.dunlap@eu.citrix.com>

And seen elsewhere:

Reviewed-by: Dario Faggioli<dario.faggioli@citrix.com>


(Correct me if this is the wrong patch, Dario!)

Thanks, Nathan!

  -George

Re: [Patch] credit: Update other parameters when setting tslice_ms

[Dario Faggioli]

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On ven, 2013-11-15 at 12:25 +0000, George Dunlap wrote:
> On 13/11/13 21:49, Nathan Studer wrote:
> > 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>
> 
> Reviewed-by: George Dunlap <george.dunlap@eu.citrix.com>
> 
> And seen elsewhere:
> 
> Reviewed-by: Dario Faggioli<dario.faggioli@citrix.com>
> 
This is perfect, thanks a lot. :-)

Dario

-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)


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