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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH RFC 38/49] xen/sched: move struct task_slice into struct sched_item
In order to prepare for multiple vcpus per schedule item move struct
task_slice in schedule() from the local stack into struct sched_item
of the currently running item. To make access easier for the single
schedulers add the pointer of the currently running item as a parameter
of do_schedule().
While at it switch the tasklet_work_scheduled parameter of
do_schedule() from bool_t to bool.
As struct task_slice is only ever modified with the local schedule
lock held it is safe to directly set the different items in struct
sched_item instead of using an on-stack copy for returning the data.
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
xen/common/sched_arinc653.c | 20 +++++++-------------
xen/common/sched_credit.c | 25 +++++++++++--------------
xen/common/sched_credit2.c | 21 +++++++++------------
xen/common/sched_null.c | 26 ++++++++++++--------------
xen/common/sched_rt.c | 22 +++++++++++-----------
xen/common/schedule.c | 21 ++++++++++-----------
xen/include/xen/sched-if.h | 17 +++++++++--------
7 files changed, 69 insertions(+), 83 deletions(-)
diff --git a/xen/common/sched_arinc653.c b/xen/common/sched_arinc653.c
index 3919c0a3e9..e98e98116b 100644
--- a/xen/common/sched_arinc653.c
+++ b/xen/common/sched_arinc653.c
@@ -497,18 +497,14 @@ a653sched_item_wake(const struct scheduler *ops, struct
sched_item *item)
*
* @param ops Pointer to this instance of the scheduler structure
* @param now Current time
- *
- * @return Address of the ITEM structure scheduled to be run next
- * Amount of time to execute the returned ITEM
- * Flag for whether the ITEM was migrated
*/
-static struct task_slice
+static void
a653sched_do_schedule(
const struct scheduler *ops,
+ struct sched_item *prev,
s_time_t now,
- bool_t tasklet_work_scheduled)
+ bool tasklet_work_scheduled)
{
- struct task_slice ret; /* hold the chosen domain */
struct sched_item *new_task = NULL;
static unsigned int sched_index = 0;
static s_time_t next_switch_time;
@@ -586,13 +582,11 @@ a653sched_do_schedule(
* Return the amount of time the next domain has to run and the address
* of the selected task's ITEM structure.
*/
- ret.time = next_switch_time - now;
- ret.task = new_task;
- ret.migrated = 0;
-
- BUG_ON(ret.time <= 0);
+ prev->next_time = next_switch_time - now;
+ prev->next_task = new_task;
+ new_task->migrated = false;
- return ret;
+ BUG_ON(prev->next_time <= 0);
}
/**
diff --git a/xen/common/sched_credit.c b/xen/common/sched_credit.c
index 4734f52fc7..064f88ab23 100644
--- a/xen/common/sched_credit.c
+++ b/xen/common/sched_credit.c
@@ -1689,7 +1689,7 @@ csched_runq_steal(int peer_cpu, int cpu, int pri, int
balance_step)
static struct csched_item *
csched_load_balance(struct csched_private *prv, int cpu,
- struct csched_item *snext, bool_t *stolen)
+ struct csched_item *snext, bool *stolen)
{
struct cpupool *c = per_cpu(cpupool, cpu);
struct csched_item *speer;
@@ -1805,7 +1805,7 @@ csched_load_balance(struct csched_private *prv, int cpu,
/* As soon as one item is found, balancing ends */
if ( speer != NULL )
{
- *stolen = 1;
+ *stolen = true;
/*
* Next time we'll look for work to steal on this node, we
* will start from the next pCPU, with respect to this one,
@@ -1835,19 +1835,18 @@ csched_load_balance(struct csched_private *prv, int cpu,
* This function is in the critical path. It is designed to be simple and
* fast for the common case.
*/
-static struct task_slice
-csched_schedule(
- const struct scheduler *ops, s_time_t now, bool_t tasklet_work_scheduled)
+static void csched_schedule(
+ const struct scheduler *ops, struct sched_item *item, s_time_t now,
+ bool tasklet_work_scheduled)
{
const unsigned int cpu = smp_processor_id();
const unsigned int sched_cpu = sched_get_resource_cpu(cpu);
struct list_head * const runq = RUNQ(sched_cpu);
- struct sched_item *item = current->sched_item;
struct csched_item * const scurr = CSCHED_ITEM(item);
struct csched_private *prv = CSCHED_PRIV(ops);
struct csched_item *snext;
- struct task_slice ret;
s_time_t runtime, tslice;
+ bool migrated = false;
SCHED_STAT_CRANK(schedule);
CSCHED_ITEM_CHECK(item);
@@ -1937,7 +1936,6 @@ csched_schedule(
(unsigned char *)&d);
}
- ret.migrated = 0;
goto out;
}
tslice = prv->tslice;
@@ -1955,7 +1953,6 @@ csched_schedule(
}
snext = __runq_elem(runq->next);
- ret.migrated = 0;
/* Tasklet work (which runs in idle ITEM context) overrides all else. */
if ( tasklet_work_scheduled )
@@ -1981,7 +1978,7 @@ csched_schedule(
if ( snext->pri > CSCHED_PRI_TS_OVER )
__runq_remove(snext);
else
- snext = csched_load_balance(prv, sched_cpu, snext, &ret.migrated);
+ snext = csched_load_balance(prv, sched_cpu, snext, &migrated);
/*
* Update idlers mask if necessary. When we're idling, other CPUs
@@ -2004,12 +2001,12 @@ out:
/*
* Return task to run next...
*/
- ret.time = (is_idle_item(snext->item) ?
+ item->next_time = (is_idle_item(snext->item) ?
-1 : tslice);
- ret.task = snext->item;
+ item->next_task = snext->item;
+ snext->item->migrated = migrated;
- CSCHED_ITEM_CHECK(ret.task);
- return ret;
+ CSCHED_ITEM_CHECK(item->next_task);
}
static void
diff --git a/xen/common/sched_credit2.c b/xen/common/sched_credit2.c
index d5cb8c0200..f1074be25d 100644
--- a/xen/common/sched_credit2.c
+++ b/xen/common/sched_credit2.c
@@ -3443,19 +3443,18 @@ runq_candidate(struct csched2_runqueue_data *rqd,
* This function is in the critical path. It is designed to be simple and
* fast for the common case.
*/
-static struct task_slice
-csched2_schedule(
- const struct scheduler *ops, s_time_t now, bool tasklet_work_scheduled)
+static void csched2_schedule(
+ const struct scheduler *ops, struct sched_item *curritem, s_time_t now,
+ bool tasklet_work_scheduled)
{
const unsigned int cpu = smp_processor_id();
const unsigned int sched_cpu = sched_get_resource_cpu(cpu);
struct csched2_runqueue_data *rqd;
- struct sched_item *curritem = current->sched_item;
struct csched2_item * const scurr = csched2_item(curritem);
struct csched2_item *snext = NULL;
unsigned int skipped_items = 0;
- struct task_slice ret;
bool tickled;
+ bool migrated = false;
SCHED_STAT_CRANK(schedule);
CSCHED2_ITEM_CHECK(curritem);
@@ -3540,8 +3539,6 @@ csched2_schedule(
&& item_runnable(curritem) )
__set_bit(__CSFLAG_delayed_runq_add, &scurr->flags);
- ret.migrated = 0;
-
/* Accounting for non-idle tasks */
if ( !is_idle_item(snext->item) )
{
@@ -3591,7 +3588,7 @@ csched2_schedule(
snext->credit += CSCHED2_MIGRATE_COMPENSATION;
sched_set_res(snext->item, per_cpu(sched_res, sched_cpu));
SCHED_STAT_CRANK(migrated);
- ret.migrated = 1;
+ migrated = true;
}
}
else
@@ -3622,11 +3619,11 @@ csched2_schedule(
/*
* Return task to run next...
*/
- ret.time = csched2_runtime(ops, sched_cpu, snext, now);
- ret.task = snext->item;
+ curritem->next_time = csched2_runtime(ops, sched_cpu, snext, now);
+ curritem->next_task = snext->item;
+ snext->item->migrated = migrated;
- CSCHED2_ITEM_CHECK(ret.task);
- return ret;
+ CSCHED2_ITEM_CHECK(curritem->next_task);
}
static void
diff --git a/xen/common/sched_null.c b/xen/common/sched_null.c
index 34ce7a05d3..1af396dcdb 100644
--- a/xen/common/sched_null.c
+++ b/xen/common/sched_null.c
@@ -703,16 +703,14 @@ static inline void null_item_check(struct sched_item
*item)
* - the item assigned to the pCPU, if there's one and it can run;
* - the idle item, otherwise.
*/
-static struct task_slice null_schedule(const struct scheduler *ops,
- s_time_t now,
- bool_t tasklet_work_scheduled)
+static void null_schedule(const struct scheduler *ops, struct sched_item *prev,
+ s_time_t now, bool tasklet_work_scheduled)
{
unsigned int bs;
const unsigned int cpu = smp_processor_id();
const unsigned int sched_cpu = sched_get_resource_cpu(cpu);
struct null_private *prv = null_priv(ops);
struct null_item *wvc;
- struct task_slice ret;
SCHED_STAT_CRANK(schedule);
NULL_ITEM_CHECK(current->sched_item);
@@ -740,19 +738,18 @@ static struct task_slice null_schedule(const struct
scheduler *ops,
if ( tasklet_work_scheduled )
{
trace_var(TRC_SNULL_TASKLET, 1, 0, NULL);
- ret.task = sched_idle_item(sched_cpu);
+ prev->next_task = sched_idle_item(sched_cpu);
}
else
- ret.task = per_cpu(npc, sched_cpu).item;
- ret.migrated = 0;
- ret.time = -1;
+ prev->next_task = per_cpu(npc, sched_cpu).item;
+ prev->next_time = -1;
/*
* We may be new in the cpupool, or just coming back online. In which
* case, there may be items in the waitqueue that we can assign to us
* and run.
*/
- if ( unlikely(ret.task == NULL) )
+ if ( unlikely(prev->next_task == NULL) )
{
spin_lock(&prv->waitq_lock);
@@ -778,7 +775,7 @@ static struct task_slice null_schedule(const struct
scheduler *ops,
{
item_assign(prv, wvc->item, sched_cpu);
list_del_init(&wvc->waitq_elem);
- ret.task = wvc->item;
+ prev->next_task = wvc->item;
goto unlock;
}
}
@@ -787,11 +784,12 @@ static struct task_slice null_schedule(const struct
scheduler *ops,
spin_unlock(&prv->waitq_lock);
}
- if ( unlikely(ret.task == NULL || !item_runnable(ret.task)) )
- ret.task = sched_idle_item(sched_cpu);
+ if ( unlikely(prev->next_task == NULL || !item_runnable(prev->next_task)) )
+ prev->next_task = sched_idle_item(sched_cpu);
- NULL_ITEM_CHECK(ret.task);
- return ret;
+ NULL_ITEM_CHECK(prev->next_task);
+
+ prev->next_task->migrated = false;
}
static inline void dump_item(struct null_private *prv, struct null_item *nvc)
diff --git a/xen/common/sched_rt.c b/xen/common/sched_rt.c
index 2366e33beb..c5e8b559f3 100644
--- a/xen/common/sched_rt.c
+++ b/xen/common/sched_rt.c
@@ -1062,16 +1062,16 @@ runq_pick(const struct scheduler *ops, const cpumask_t
*mask)
* schedule function for rt scheduler.
* The lock is already grabbed in schedule.c, no need to lock here
*/
-static struct task_slice
-rt_schedule(const struct scheduler *ops, s_time_t now, bool_t
tasklet_work_scheduled)
+static void
+rt_schedule(const struct scheduler *ops, struct sched_item *curritem,
+ s_time_t now, bool tasklet_work_scheduled)
{
const unsigned int cpu = smp_processor_id();
const unsigned int sched_cpu = sched_get_resource_cpu(cpu);
struct rt_private *prv = rt_priv(ops);
- struct rt_item *const scurr = rt_item(current->sched_item);
+ struct rt_item *const scurr = rt_item(curritem);
struct rt_item *snext = NULL;
- struct task_slice ret = { .migrated = 0 };
- struct sched_item *curritem = current->sched_item;
+ bool migrated = false;
/* TRACE */
{
@@ -1119,7 +1119,7 @@ rt_schedule(const struct scheduler *ops, s_time_t now,
bool_t tasklet_work_sched
__set_bit(__RTDS_delayed_runq_add, &scurr->flags);
snext->last_start = now;
- ret.time = -1; /* if an idle item is picked */
+ curritem->next_time = -1; /* if an idle item is picked */
if ( !is_idle_item(snext->item) )
{
if ( snext != scurr )
@@ -1130,13 +1130,13 @@ rt_schedule(const struct scheduler *ops, s_time_t now,
bool_t tasklet_work_sched
if ( sched_item_cpu(snext->item) != sched_cpu )
{
sched_set_res(snext->item, per_cpu(sched_res, sched_cpu));
- ret.migrated = 1;
+ migrated = true;
}
- ret.time = snext->cur_budget; /* invoke the scheduler next time */
+ /* Invoke the scheduler next time. */
+ curritem->next_time = snext->cur_budget;
}
- ret.task = snext->item;
-
- return ret;
+ curritem->next_task = snext->item;
+ snext->item->migrated = migrated;
}
/*
diff --git a/xen/common/schedule.c b/xen/common/schedule.c
index 22e43d88cc..082225d173 100644
--- a/xen/common/schedule.c
+++ b/xen/common/schedule.c
@@ -1611,10 +1611,9 @@ static void schedule(void)
s_time_t now;
struct scheduler *sched;
unsigned long *tasklet_work = &this_cpu(tasklet_work_to_do);
- bool_t tasklet_work_scheduled = 0;
+ bool tasklet_work_scheduled = false;
struct sched_resource *sd;
spinlock_t *lock;
- struct task_slice next_slice;
int cpu = smp_processor_id();
ASSERT_NOT_IN_ATOMIC();
@@ -1630,12 +1629,12 @@ static void schedule(void)
set_bit(_TASKLET_scheduled, tasklet_work);
/* fallthrough */
case TASKLET_enqueued|TASKLET_scheduled:
- tasklet_work_scheduled = 1;
+ tasklet_work_scheduled = true;
break;
case TASKLET_scheduled:
clear_bit(_TASKLET_scheduled, tasklet_work);
case 0:
- /*tasklet_work_scheduled = 0;*/
+ /*tasklet_work_scheduled = false;*/
break;
default:
BUG();
@@ -1649,14 +1648,14 @@ static void schedule(void)
/* get policy-specific decision on scheduling... */
sched = this_cpu(scheduler);
- next_slice = sched->do_schedule(sched, now, tasklet_work_scheduled);
+ sched->do_schedule(sched, prev, now, tasklet_work_scheduled);
- next = next_slice.task;
+ next = prev->next_task;
sd->curr = next;
- if ( next_slice.time >= 0 ) /* -ve means no limit */
- set_timer(&sd->s_timer, now + next_slice.time);
+ if ( prev->next_time >= 0 ) /* -ve means no limit */
+ set_timer(&sd->s_timer, now + prev->next_time);
if ( unlikely(prev == next) )
{
@@ -1664,7 +1663,7 @@ static void schedule(void)
TRACE_4D(TRC_SCHED_SWITCH_INFCONT,
next->domain->domain_id, next->item_id,
now - prev->state_entry_time,
- next_slice.time);
+ prev->next_time);
trace_continue_running(next->vcpu);
return continue_running(prev->vcpu);
}
@@ -1676,7 +1675,7 @@ static void schedule(void)
next->domain->domain_id, next->item_id,
(next->vcpu->runstate.state == RUNSTATE_runnable) ?
(now - next->state_entry_time) : 0,
- next_slice.time);
+ prev->next_time);
ASSERT(prev->vcpu->runstate.state == RUNSTATE_running);
@@ -1705,7 +1704,7 @@ static void schedule(void)
stop_timer(&prev->vcpu->periodic_timer);
- if ( next_slice.migrated )
+ if ( next->migrated )
vcpu_move_irqs(next->vcpu);
vcpu_periodic_timer_work(next->vcpu);
diff --git a/xen/include/xen/sched-if.h b/xen/include/xen/sched-if.h
index 795b2fafe5..e2bc8f7284 100644
--- a/xen/include/xen/sched-if.h
+++ b/xen/include/xen/sched-if.h
@@ -72,6 +72,8 @@ struct sched_item {
bool affinity_broken;
/* Does soft affinity actually play a role (given hard affinity)? */
bool soft_aff_effective;
+ /* Item has been migrated to other cpu(s). */
+ bool migrated;
/* Bitmask of CPUs on which this VCPU may run. */
cpumask_var_t cpu_hard_affinity;
/* Used to change affinity temporarily. */
@@ -80,6 +82,10 @@ struct sched_item {
cpumask_var_t cpu_hard_affinity_saved;
/* Bitmask of CPUs on which this VCPU prefers to run. */
cpumask_var_t cpu_soft_affinity;
+
+ /* Next item to run. */
+ struct sched_item *next_task;
+ s_time_t next_time;
};
#define for_each_sched_item(d, e) \
@@ -225,12 +231,6 @@ static inline spinlock_t *pcpu_schedule_trylock(unsigned
int cpu)
return NULL;
}
-struct task_slice {
- struct sched_item *task;
- s_time_t time;
- bool_t migrated;
-};
-
struct scheduler {
char *name; /* full name for this scheduler */
char *opt_name; /* option name for this scheduler */
@@ -273,8 +273,9 @@ struct scheduler {
void (*context_saved) (const struct scheduler *,
struct sched_item *);
- struct task_slice (*do_schedule) (const struct scheduler *, s_time_t,
- bool_t tasklet_work_scheduled);
+ void (*do_schedule) (const struct scheduler *,
+ struct sched_item *, s_time_t,
+ bool tasklet_work_scheduled);
struct sched_resource * (*pick_resource) (const struct scheduler *,
struct sched_item *);
--
2.16.4
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