From: Juergen Gross <jgross@suse.com>
To: xen-devel@lists.xenproject.org
Cc: Juergen Gross <jgross@suse.com>, Tim Deegan <tim@xen.org>,
Stefano Stabellini <sstabellini@kernel.org>, Wei Liu <wl@xen.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
George Dunlap <george.dunlap@eu.citrix.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Ian Jackson <ian.jackson@eu.citrix.com>,
Dario Faggioli <dfaggioli@suse.com>,
Julien Grall <julien.grall@arm.com>,
Jan Beulich <jbeulich@suse.com>
Subject: [Xen-devel] [PATCH v2 36/48] xen/sched: make vcpu_wake() and vcpu_sleep() core scheduling aware
Date: Fri, 9 Aug 2019 16:58:21 +0200 [thread overview]
Message-ID: <20190809145833.1020-37-jgross@suse.com> (raw)
In-Reply-To: <20190809145833.1020-1-jgross@suse.com>
vcpu_wake() and vcpu_sleep() need to be made core scheduling aware:
they might need to switch a single vcpu of an already scheduled unit
between running and not running.
Especially when vcpu_sleep() for a vcpu is being called by a vcpu of
the same scheduling unit special care must be taken in order to avoid
a deadlock: the vcpu to be put asleep must be forced through a
context switch without doing so for the calling vcpu. For this
purpose add a vcpu flag handled in sched_slave() and in
sched_wait_rendezvous_in() allowing a vcpu of the currently running
unit to switch state at a higher priority than a normal schedule
event.
Use the same mechanism when waking up a vcpu of a currently active
unit.
While at it make vcpu_sleep_nosync_locked() static as it is used in
schedule.c only.
Signed-off-by: Juergen Gross <jgross@suse.com>
---
RFC V2: add vcpu_sleep() handling and force_context_switch flag
V2: fix runstate change in sched_force_context_switch()
---
xen/common/schedule.c | 125 ++++++++++++++++++++++++++++++++++++++++++---
xen/include/xen/sched-if.h | 9 ++--
xen/include/xen/sched.h | 2 +
3 files changed, 127 insertions(+), 9 deletions(-)
diff --git a/xen/common/schedule.c b/xen/common/schedule.c
index 5cd7d2d857..fe7ab1b4de 100644
--- a/xen/common/schedule.c
+++ b/xen/common/schedule.c
@@ -714,8 +714,10 @@ void sched_destroy_domain(struct domain *d)
}
}
-void vcpu_sleep_nosync_locked(struct vcpu *v)
+static void vcpu_sleep_nosync_locked(struct vcpu *v)
{
+ struct sched_unit *unit = v->sched_unit;
+
ASSERT(spin_is_locked(get_sched_res(v->processor)->schedule_lock));
if ( likely(!vcpu_runnable(v)) )
@@ -723,7 +725,14 @@ void vcpu_sleep_nosync_locked(struct vcpu *v)
if ( v->runstate.state == RUNSTATE_runnable )
vcpu_runstate_change(v, RUNSTATE_offline, NOW());
- sched_sleep(vcpu_scheduler(v), v->sched_unit);
+ if ( likely(!unit_runnable(unit)) )
+ sched_sleep(vcpu_scheduler(v), unit);
+ else if ( unit_running(unit) > 1 && v->is_running &&
+ !v->force_context_switch )
+ {
+ v->force_context_switch = true;
+ cpu_raise_softirq(v->processor, SCHED_SLAVE_SOFTIRQ);
+ }
}
}
@@ -755,16 +764,22 @@ void vcpu_wake(struct vcpu *v)
{
unsigned long flags;
spinlock_t *lock;
+ struct sched_unit *unit = v->sched_unit;
TRACE_2D(TRC_SCHED_WAKE, v->domain->domain_id, v->vcpu_id);
- lock = unit_schedule_lock_irqsave(v->sched_unit, &flags);
+ lock = unit_schedule_lock_irqsave(unit, &flags);
if ( likely(vcpu_runnable(v)) )
{
if ( v->runstate.state >= RUNSTATE_blocked )
vcpu_runstate_change(v, RUNSTATE_runnable, NOW());
- sched_wake(vcpu_scheduler(v), v->sched_unit);
+ sched_wake(vcpu_scheduler(v), unit);
+ if ( unit->is_running && !v->is_running && !v->force_context_switch )
+ {
+ v->force_context_switch = true;
+ cpu_raise_softirq(v->processor, SCHED_SLAVE_SOFTIRQ);
+ }
}
else if ( !(v->pause_flags & VPF_blocked) )
{
@@ -772,7 +787,7 @@ void vcpu_wake(struct vcpu *v)
vcpu_runstate_change(v, RUNSTATE_offline, NOW());
}
- unit_schedule_unlock_irqrestore(lock, flags, v->sched_unit);
+ unit_schedule_unlock_irqrestore(lock, flags, unit);
}
void vcpu_unblock(struct vcpu *v)
@@ -1981,6 +1996,62 @@ static void sched_context_switch(struct vcpu *vprev, struct vcpu *vnext,
context_switch(vprev, vnext);
}
+/*
+ * Force a context switch of a single vcpu of an unit.
+ * Might be called either if a vcpu of an already running unit is woken up
+ * or if a vcpu of a running unit is put asleep with other vcpus of the same
+ * unit still running.
+ */
+static struct vcpu *sched_force_context_switch(struct vcpu *vprev,
+ struct vcpu *v,
+ int cpu, s_time_t now)
+{
+ v->force_context_switch = false;
+
+ if ( vcpu_runnable(v) == v->is_running )
+ return NULL;
+
+ if ( vcpu_runnable(v) )
+ {
+ if ( is_idle_vcpu(vprev) )
+ {
+ vcpu_runstate_change(vprev, RUNSTATE_runnable, now);
+ vprev->sched_unit = get_sched_res(cpu)->sched_unit_idle;
+ }
+ vcpu_runstate_change(v, RUNSTATE_running, now);
+ }
+ else
+ {
+ /* Make sure not to switch last vcpu of an unit away. */
+ if ( unit_running(v->sched_unit) == 1 )
+ return NULL;
+
+ v->new_state = vcpu_runstate_blocked(v);
+ vcpu_runstate_change(v, v->new_state, now);
+ v = sched_unit2vcpu_cpu(vprev->sched_unit, cpu);
+ if ( v != vprev )
+ {
+ if ( is_idle_vcpu(vprev) )
+ {
+ vcpu_runstate_change(vprev, RUNSTATE_runnable, now);
+ vprev->sched_unit = get_sched_res(cpu)->sched_unit_idle;
+ }
+ else
+ {
+ v->sched_unit = vprev->sched_unit;
+ vcpu_runstate_change(v, RUNSTATE_running, now);
+ }
+ }
+ }
+
+ v->is_running = 1;
+
+ /* Make sure not to loose another slave call. */
+ raise_softirq(SCHED_SLAVE_SOFTIRQ);
+
+ return v;
+}
+
/*
* Rendezvous before taking a scheduling decision.
* Called with schedule lock held, so all accesses to the rendezvous counter
@@ -1996,6 +2067,7 @@ static struct sched_unit *sched_wait_rendezvous_in(struct sched_unit *prev,
s_time_t now)
{
struct sched_unit *next;
+ struct vcpu *v;
if ( !--prev->rendezvous_in_cnt )
{
@@ -2004,8 +2076,28 @@ static struct sched_unit *sched_wait_rendezvous_in(struct sched_unit *prev,
return next;
}
+ v = unit2vcpu_cpu(prev, cpu);
while ( prev->rendezvous_in_cnt )
{
+ if ( v && v->force_context_switch )
+ {
+ struct vcpu *vprev = current;
+
+ v = sched_force_context_switch(vprev, v, cpu, now);
+
+ if ( v )
+ {
+ /* We'll come back another time, so adjust rendezvous_in_cnt. */
+ prev->rendezvous_in_cnt++;
+ atomic_set(&prev->rendezvous_out_cnt, 0);
+
+ pcpu_schedule_unlock_irq(*lock, cpu);
+
+ sched_context_switch(vprev, v, false, now);
+ }
+
+ v = unit2vcpu_cpu(prev, cpu);
+ }
/*
* Coming from idle might need to do tasklet work.
* In order to avoid deadlocks we can't do that here, but have to
@@ -2038,10 +2130,11 @@ static struct sched_unit *sched_wait_rendezvous_in(struct sched_unit *prev,
static void sched_slave(void)
{
- struct vcpu *vprev = current;
+ struct vcpu *v, *vprev = current;
struct sched_unit *prev = vprev->sched_unit, *next;
s_time_t now;
spinlock_t *lock;
+ bool do_softirq = false;
int cpu = smp_processor_id();
ASSERT_NOT_IN_ATOMIC();
@@ -2050,9 +2143,29 @@ static void sched_slave(void)
now = NOW();
+ v = unit2vcpu_cpu(prev, cpu);
+ if ( v && v->force_context_switch )
+ {
+ v = sched_force_context_switch(vprev, v, cpu, now);
+
+ if ( v )
+ {
+ pcpu_schedule_unlock_irq(lock, cpu);
+
+ sched_context_switch(vprev, v, false, now);
+ }
+
+ do_softirq = true;
+ }
+
if ( !prev->rendezvous_in_cnt )
{
pcpu_schedule_unlock_irq(lock, cpu);
+
+ /* Check for failed forced context switch. */
+ if ( do_softirq )
+ raise_softirq(SCHEDULE_SOFTIRQ);
+
return;
}
diff --git a/xen/include/xen/sched-if.h b/xen/include/xen/sched-if.h
index 3ac7757c0d..eb6b9ef55c 100644
--- a/xen/include/xen/sched-if.h
+++ b/xen/include/xen/sched-if.h
@@ -99,6 +99,11 @@ static inline bool unit_runnable(const struct sched_unit *unit)
return false;
}
+static inline int vcpu_runstate_blocked(struct vcpu *v)
+{
+ return (v->pause_flags & VPF_blocked) ? RUNSTATE_blocked : RUNSTATE_offline;
+}
+
static inline bool unit_runnable_state(const struct sched_unit *unit)
{
struct vcpu *v;
@@ -111,9 +116,7 @@ static inline bool unit_runnable_state(const struct sched_unit *unit)
{
runnable = vcpu_runnable(v);
- v->new_state = runnable ? RUNSTATE_running
- : (v->pause_flags & VPF_blocked)
- ? RUNSTATE_blocked : RUNSTATE_offline;
+ v->new_state = runnable ? RUNSTATE_running : vcpu_runstate_blocked(v);
if ( runnable )
ret = true;
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index ed0535946f..e868646f0e 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -186,6 +186,8 @@ struct vcpu
bool is_running;
/* VCPU should wake fast (do not deep sleep the CPU). */
bool is_urgent;
+ /* VCPU must context_switch without scheduling unit. */
+ bool force_context_switch;
#ifdef VCPU_TRAP_LAST
#define VCPU_TRAP_NONE 0
--
2.16.4
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next prev parent reply other threads:[~2019-08-09 14:59 UTC|newest]
Thread overview: 126+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-09 14:57 [Xen-devel] [PATCH v2 00/48] xen: add core scheduling support Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 01/48] xen/sched: use new sched_unit instead of vcpu in scheduler interfaces Juergen Gross
2019-09-02 9:07 ` Jan Beulich
2019-09-09 5:26 ` Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 02/48] xen/sched: move per-vcpu scheduler private data pointer to sched_unit Juergen Gross
2019-08-23 10:47 ` Dario Faggioli
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 03/48] xen/sched: build a linked list of struct sched_unit Juergen Gross
2019-08-23 10:52 ` Dario Faggioli
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 04/48] xen/sched: introduce struct sched_resource Juergen Gross
2019-08-23 10:54 ` Dario Faggioli
2019-09-04 13:10 ` Jan Beulich
2019-09-09 5:31 ` Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 05/48] xen/sched: let pick_cpu return a scheduler resource Juergen Gross
2019-09-04 13:34 ` Jan Beulich
2019-09-09 5:43 ` Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 06/48] xen/sched: switch schedule_data.curr to point at sched_unit Juergen Gross
2019-09-04 13:36 ` Jan Beulich
2019-09-09 5:46 ` Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 07/48] xen/sched: move per cpu scheduler private data into struct sched_resource Juergen Gross
2019-09-04 13:48 ` Jan Beulich
2019-09-05 7:13 ` Juergen Gross
2019-09-05 7:38 ` Jan Beulich
2019-09-09 13:03 ` Dario Faggioli
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 08/48] xen/sched: switch vcpu_schedule_lock to unit_schedule_lock Juergen Gross
2019-09-04 14:02 ` Jan Beulich
2019-09-04 14:41 ` Juergen Gross
2019-09-04 14:54 ` Jan Beulich
2019-09-04 15:02 ` Juergen Gross
2019-09-11 16:02 ` Dario Faggioli
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 09/48] xen/sched: move some per-vcpu items to struct sched_unit Juergen Gross
2019-09-04 14:16 ` Jan Beulich
2019-09-09 6:39 ` Juergen Gross
2019-09-09 6:55 ` Jan Beulich
2019-09-09 7:05 ` Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 10/48] xen/sched: add scheduler helpers hiding vcpu Juergen Gross
2019-09-04 14:49 ` Jan Beulich
2019-09-11 13:22 ` Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 11/48] xen/sched: rename scheduler related perf counters Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 12/48] xen/sched: switch struct task_slice from vcpu to sched_unit Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 13/48] xen/sched: add is_running indicator to struct sched_unit Juergen Gross
2019-09-04 15:06 ` Jan Beulich
2019-09-11 13:44 ` Juergen Gross
2019-09-11 15:06 ` Jan Beulich
2019-09-11 15:32 ` Juergen Gross
2019-08-09 14:57 ` [Xen-devel] [PATCH v2 14/48] xen/sched: make null scheduler vcpu agnostic Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 15/48] xen/sched: make rt " Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 16/48] xen/sched: make credit " Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 17/48] xen/sched: make credit2 " Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 18/48] xen/sched: make arinc653 " Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 19/48] xen: add sched_unit_pause_nosync() and sched_unit_unpause() Juergen Gross
2019-09-09 13:34 ` Jan Beulich
2019-09-11 14:15 ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 20/48] xen: let vcpu_create() select processor Juergen Gross
2019-08-23 16:42 ` Julien Grall
2019-09-09 13:38 ` Jan Beulich
2019-09-11 14:22 ` Juergen Gross
2019-09-11 17:20 ` Dario Faggioli
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 21/48] xen/sched: use sched_resource cpu instead smp_processor_id in schedulers Juergen Gross
2019-09-09 14:17 ` Jan Beulich
2019-09-12 9:34 ` Juergen Gross
2019-09-12 10:04 ` Jan Beulich
2019-09-12 11:03 ` Juergen Gross
2019-09-12 11:17 ` Juergen Gross
2019-09-12 11:46 ` Jan Beulich
2019-09-12 11:53 ` Juergen Gross
2019-09-12 12:08 ` Jan Beulich
2019-09-12 12:13 ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 22/48] xen/sched: switch schedule() from vcpus to sched_units Juergen Gross
2019-09-09 14:35 ` Jan Beulich
2019-09-12 13:44 ` Juergen Gross
2019-09-12 14:34 ` Jan Beulich
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 23/48] xen/sched: switch sched_move_irqs() to take sched_unit as parameter Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 24/48] xen: switch from for_each_vcpu() to for_each_sched_unit() Juergen Gross
2019-09-09 15:14 ` Jan Beulich
2019-09-12 14:02 ` Juergen Gross
2019-09-12 14:40 ` Jan Beulich
2019-09-12 14:47 ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 25/48] xen/sched: add runstate counters to struct sched_unit Juergen Gross
2019-09-09 14:30 ` Jan Beulich
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 26/48] xen/sched: rework and rename vcpu_force_reschedule() Juergen Gross
2019-09-10 14:06 ` Jan Beulich
2019-09-13 9:33 ` Juergen Gross
2019-09-13 9:40 ` Jan Beulich
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 27/48] xen/sched: Change vcpu_migrate_*() to operate on schedule unit Juergen Gross
2019-09-10 15:11 ` Jan Beulich
2019-09-13 12:33 ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 28/48] xen/sched: move struct task_slice into struct sched_unit Juergen Gross
2019-09-10 15:18 ` Jan Beulich
2019-09-13 12:56 ` Juergen Gross
2019-09-12 8:13 ` Dario Faggioli
2019-09-12 8:21 ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 29/48] xen/sched: add code to sync scheduling of all vcpus of a sched unit Juergen Gross
2019-09-10 15:36 ` Jan Beulich
2019-09-13 13:12 ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 30/48] xen/sched: introduce unit_runnable_state() Juergen Gross
2019-09-11 10:30 ` Jan Beulich
2019-09-12 10:22 ` Dario Faggioli
2019-09-13 14:07 ` Juergen Gross
2019-09-13 14:44 ` Jan Beulich
2019-09-13 15:23 ` Juergen Gross
2019-09-12 10:24 ` Dario Faggioli
2019-09-13 14:14 ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 31/48] xen/sched: add support for multiple vcpus per sched unit where missing Juergen Gross
2019-09-11 10:43 ` Jan Beulich
2019-09-13 15:01 ` Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 32/48] xen/sched: modify cpupool_domain_cpumask() to be an unit mask Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 33/48] xen/sched: support allocating multiple vcpus into one sched unit Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 34/48] xen/sched: add a percpu resource index Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 35/48] xen/sched: add fall back to idle vcpu when scheduling unit Juergen Gross
2019-09-11 11:33 ` Julien Grall
2019-08-09 14:58 ` Juergen Gross [this message]
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 37/48] xen/sched: carve out freeing sched_unit memory into dedicated function Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 38/48] xen/sched: move per-cpu variable scheduler to struct sched_resource Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 39/48] xen/sched: move per-cpu variable cpupool " Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 40/48] xen/sched: reject switching smt on/off with core scheduling active Juergen Gross
2019-09-10 15:47 ` Jan Beulich
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 41/48] xen/sched: prepare per-cpupool scheduling granularity Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 42/48] xen/sched: split schedule_cpu_switch() Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 43/48] xen/sched: protect scheduling resource via rcu Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 44/48] xen/sched: support multiple cpus per scheduling resource Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 45/48] xen/sched: support differing granularity in schedule_cpu_[add/rm]() Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 46/48] xen/sched: support core scheduling for moving cpus to/from cpupools Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 47/48] xen/sched: disable scheduling when entering ACPI deep sleep states Juergen Gross
2019-08-09 14:58 ` [Xen-devel] [PATCH v2 48/48] xen/sched: add scheduling granularity enum Juergen Gross
2019-08-15 10:17 ` [Xen-devel] [PATCH v2 00/48] xen: add core scheduling support Sergey Dyasli
2019-09-05 6:22 ` Juergen Gross
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