Re: [PATCH] only set scheduler timer for non-idle CPU

[Thomas Pfeuffer <thomas.pfeuffer@mytum.de>]

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Hello Ke,

>It is not necessary to set scheduler timer for idle CPU. so this patch add conditional check for idle CPU.
>  
>
I think your patch is not good in case sedf-scheduler is used. If idle 
VCPU is the current "running" VCPU, the scheduler timer is set to the 
next "period begin" of the first VCPU in the wait queue.
Your patch prevents sedf from taking the VCPUs waiting for their next 
period into the runnable queue again.

Best regards,

Thomas

>Signed-off-by:  Yu Ke <ke.yu@intel.com>
>                Tian Kevin <kevin.tian@intel.com>
>
>diff -r e4bfa70d587c xen/common/schedule.c
>--- a/xen/common/schedule.c
>+++ b/xen/common/schedule.c
>@@ -819,7 +819,10 @@ static void schedule(void)
> 
>     sd->curr = next;
>     
>-    set_timer(&sd->s_timer, now + r_time);
>+    if ( !is_idle_vcpu(next) )
>+    {
>+        set_timer(&sd->s_timer, now + r_time);
>+    }
> 
>     if ( unlikely(prev == next) )
>     {
>  
>
>------------------------------------------------------------------------
>
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>  
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