--
Juergen Gross Principal Developer
IP SW OS6 Telephone: +49 (0) 89 636 47950
Fujitsu Siemens Computers e-mail: juergen.gross@xxxxxxxxxxxxxxxxxxx
Otto-Hahn-Ring 6 Internet: www.fujitsu-siemens.com
D-81739 Muenchen Company details: www.fujitsu-siemens.com/imprint.html
Add possibility for guest to mark a vcpu not to be descheduled.
Signed-off-by: juergen.gross@xxxxxxxxxxxxxxxxxxx
# HG changeset patch
# User juergen.gross@xxxxxxxxxxxxxxxxxxx
# Date 1229510869 -3600
# Node ID a854d67dd0f0aa11986d0ed741681cf671ceb7ac
# Parent a76b4e00e1862035240ec6403a8f081be61b1e2b
added support of vcpu preempt disable
diff -r a76b4e00e186 -r a854d67dd0f0 xen/common/schedule.c
--- a/xen/common/schedule.c Tue Dec 16 13:14:25 2008 +0000
+++ b/xen/common/schedule.c Wed Dec 17 11:47:49 2008 +0100
@@ -778,6 +778,7 @@ static void schedule(void)
struct schedule_data *sd;
struct task_slice next_slice;
s32 r_time; /* time for new dom to run */
+ int is_idle = is_idle_domain(prev->domain);
ASSERT(!in_irq());
ASSERT(this_cpu(mc_state).flags == 0);
@@ -787,6 +788,22 @@ static void schedule(void)
sd = &this_cpu(schedule_data);
spin_lock_irq(&sd->schedule_lock);
+
+ if ( !is_idle && unlikely(vcpu_info(prev, no_desched)) )
+ {
+ if ( !vcpu_info(prev, desched_delay) )
+ {
+ vcpu_info(prev, desched_delay) = 1;
+ sd->delay_desched = now + MILLISECS(1);
+ stop_timer(&sd->s_timer);
+ set_timer(&sd->s_timer, sd->delay_desched);
+ }
+ if ( now < sd->delay_desched )
+ {
+ spin_unlock_irq(&sd->schedule_lock);
+ return continue_running(prev);
+ }
+ }
stop_timer(&sd->s_timer);
@@ -797,6 +814,11 @@ static void schedule(void)
next = next_slice.task;
sd->curr = next;
+ sd->delay_desched = 0;
+ if ( !is_idle )
+ {
+ vcpu_info(prev, desched_delay) = 0;
+ }
set_timer(&sd->s_timer, now + r_time);
diff -r a76b4e00e186 -r a854d67dd0f0 xen/include/public/xen.h
--- a/xen/include/public/xen.h Tue Dec 16 13:14:25 2008 +0000
+++ b/xen/include/public/xen.h Wed Dec 17 11:47:49 2008 +0100
@@ -434,9 +434,18 @@ struct vcpu_info {
* non-zero mask therefore guarantees that the VCPU will not receive
* an upcall activation. The mask is cleared when the VCPU requests
* to block: this avoids wakeup-waiting races.
+ *
+ * The guest can set 'no_desched' to a non-zero value to avoid being
+ * descheduled. If the hypervisor didn't deschedule the VCPU due to
+ * 'no_desched' being set, it will itself set 'desched_delay' to inform
+ * the guest to give up control voluntaryly later. This is just a wish
+ * of the guest which the hypervisor may not obey (and it will deschedule
+ * the guest after a reasonable time anyway).
*/
uint8_t evtchn_upcall_pending;
uint8_t evtchn_upcall_mask;
+ uint8_t no_desched;
+ uint8_t desched_delay;
unsigned long evtchn_pending_sel;
struct arch_vcpu_info arch;
struct vcpu_time_info time;
diff -r a76b4e00e186 -r a854d67dd0f0 xen/include/xen/sched-if.h
--- a/xen/include/xen/sched-if.h Tue Dec 16 13:14:25 2008 +0000
+++ b/xen/include/xen/sched-if.h Wed Dec 17 11:47:49 2008 +0100
@@ -16,6 +16,7 @@ struct schedule_data {
struct vcpu *idle; /* idle task for this cpu */
void *sched_priv;
struct timer s_timer; /* scheduling timer */
+ s_time_t delay_desched; /* time of delayed deschedule */
} __cacheline_aligned;
DECLARE_PER_CPU(struct schedule_data, schedule_data);
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