[PATCH] xen: sched: get rid of cpupool_scheduler_cpumask()

[PATCH] xen: sched: get rid of cpupool_scheduler_cpumask()

[Dario Faggioli]

Hi everyone,

This was patch 4 of a series, v2 of which is in this thread:

http://lists.xen.org/archives/html/xen-devel/2015-07/msg00573.html

The first 3 patches have been applied long ago. However, I just noticed that
this one has not (unless I'm missing something).

I guess George never got round to look at it again, after v1, and formally Ack
it, and hence it has been forgotten... by me as well! :-O

As stated at the link above, it really should be straightforward, as v1 was
basically ok already, and this incorporates all of George's points and
suggestions.

It's nothing high priority, but I think it is an improvement, and therefore I'm
resubmitting it.

Regards,
Dario
---
Dario Faggioli (1):
      xen: sched: get rid of cpupool_scheduler_cpumask()

 xen/common/domain.c         |    5 +++--
 xen/common/domctl.c         |    4 ++--
 xen/common/sched_arinc653.c |    2 +-
 xen/common/sched_credit.c   |    8 +++-----
 xen/common/sched_rt.c       |   12 ++++++------
 xen/common/schedule.c       |    2 +-
 xen/include/xen/sched-if.h  |   12 ++++++++++--
 7 files changed, 26 insertions(+), 19 deletions(-)

--
<<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)

[PATCH] xen: sched: get rid of cpupool_scheduler_cpumask()

[Dario Faggioli]

and of (almost every) direct use of cpupool_online_cpumask().

In fact, what we really want for the most of the times,
is the set of valid pCPUs of the cpupool a certain domain
is part of. Furthermore, in case it's called with a NULL
pool as argument, cpupool_scheduler_cpumask() does more
harm than good, by returning the bitmask of free pCPUs!

This commit, therefore:
 * gets rid of cpupool_scheduler_cpumask(), in favour of
   cpupool_domain_cpumask(), which makes it more evident
   what we are after, and accommodates some sanity checking;
 * replaces some of the calls to cpupool_online_cpumask()
   with calls to the new functions too.

Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Acked-by: Juergen Gross <jgross@suse.com>
Acked-by: Joshua Whitehead <josh.whitehead@dornerworks.com>
Reviewed-by: Meng Xu <mengxu@cis.upenn.edu>
---
Cc: George Dunlap <george.dunlap@eu.citrix.com>
Cc: Robert VanVossen <robert.vanvossen@dornerworks.com>
Cc: Jan Beulich <jbeulich@suse.com>
---
 xen/common/domain.c         |    5 +++--
 xen/common/domctl.c         |    4 ++--
 xen/common/sched_arinc653.c |    2 +-
 xen/common/sched_credit.c   |    8 +++-----
 xen/common/sched_rt.c       |   12 ++++++------
 xen/common/schedule.c       |    2 +-
 xen/include/xen/sched-if.h  |   12 ++++++++++--
 7 files changed, 26 insertions(+), 19 deletions(-)

diff --git a/xen/common/domain.c b/xen/common/domain.c
index 8e7a282..cda60a9 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -191,7 +191,8 @@ struct vcpu *alloc_vcpu(
     /* Must be called after making new vcpu visible to for_each_vcpu(). */
     vcpu_check_shutdown(v);
 
-    domain_update_node_affinity(d);
+    if ( !is_idle_domain(d) )
+        domain_update_node_affinity(d);
 
     return v;
 }
@@ -444,7 +445,7 @@ void domain_update_node_affinity(struct domain *d)
         return;
     }
 
-    online = cpupool_online_cpumask(d->cpupool);
+    online = cpupool_domain_cpumask(d);
 
     spin_lock(&d->node_affinity_lock);
 
diff --git a/xen/common/domctl.c b/xen/common/domctl.c
index 9e0fef5..08de32d 100644
--- a/xen/common/domctl.c
+++ b/xen/common/domctl.c
@@ -664,7 +664,7 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
             goto maxvcpu_out;
 
         ret = -ENOMEM;
-        online = cpupool_online_cpumask(d->cpupool);
+        online = cpupool_domain_cpumask(d);
         if ( max > d->max_vcpus )
         {
             struct vcpu **vcpus;
@@ -757,7 +757,7 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
         if ( op->cmd == XEN_DOMCTL_setvcpuaffinity )
         {
             cpumask_var_t new_affinity, old_affinity;
-            cpumask_t *online = cpupool_online_cpumask(v->domain->cpupool);;
+            cpumask_t *online = cpupool_domain_cpumask(v->domain);;
 
             /*
              * We want to be able to restore hard affinity if we are trying
diff --git a/xen/common/sched_arinc653.c b/xen/common/sched_arinc653.c
index cff5da9..dbe02ed 100644
--- a/xen/common/sched_arinc653.c
+++ b/xen/common/sched_arinc653.c
@@ -667,7 +667,7 @@ a653sched_pick_cpu(const struct scheduler *ops, struct vcpu *vc)
      * If present, prefer vc's current processor, else
      * just find the first valid vcpu .
      */
-    online = cpupool_scheduler_cpumask(vc->domain->cpupool);
+    online = cpupool_domain_cpumask(vc->domain);
 
     cpu = cpumask_first(online);
 
diff --git a/xen/common/sched_credit.c b/xen/common/sched_credit.c
index a1945ac..27a6439 100644
--- a/xen/common/sched_credit.c
+++ b/xen/common/sched_credit.c
@@ -309,7 +309,7 @@ __runq_remove(struct csched_vcpu *svc)
 static inline int __vcpu_has_soft_affinity(const struct vcpu *vc,
                                            const cpumask_t *mask)
 {
-    return !cpumask_subset(cpupool_online_cpumask(vc->domain->cpupool),
+    return !cpumask_subset(cpupool_domain_cpumask(vc->domain),
                            vc->cpu_soft_affinity) &&
            !cpumask_subset(vc->cpu_hard_affinity, vc->cpu_soft_affinity) &&
            cpumask_intersects(vc->cpu_soft_affinity, mask);
@@ -372,9 +372,7 @@ __runq_tickle(unsigned int cpu, struct csched_vcpu *new)
     ASSERT(cur);
     cpumask_clear(&mask);
 
-    /* cpu is vc->processor, so it must be in a cpupool. */
-    ASSERT(per_cpu(cpupool, cpu) != NULL);
-    online = cpupool_online_cpumask(per_cpu(cpupool, cpu));
+    online = cpupool_domain_cpumask(new->sdom->dom);
     cpumask_and(&idle_mask, prv->idlers, online);
     idlers_empty = cpumask_empty(&idle_mask);
 
@@ -641,7 +639,7 @@ _csched_cpu_pick(const struct scheduler *ops, struct vcpu *vc, bool_t commit)
     int balance_step;
 
     /* Store in cpus the mask of online cpus on which the domain can run */
-    online = cpupool_scheduler_cpumask(vc->domain->cpupool);
+    online = cpupool_domain_cpumask(vc->domain);
     cpumask_and(&cpus, vc->cpu_hard_affinity, online);
 
     for_each_csched_balance_step( balance_step )
diff --git a/xen/common/sched_rt.c b/xen/common/sched_rt.c
index 4372486..08611c8 100644
--- a/xen/common/sched_rt.c
+++ b/xen/common/sched_rt.c
@@ -256,7 +256,7 @@ rt_dump_vcpu(const struct scheduler *ops, const struct rt_vcpu *svc)
      */
     mask = _cpumask_scratch[svc->vcpu->processor];
 
-    cpupool_mask = cpupool_scheduler_cpumask(svc->vcpu->domain->cpupool);
+    cpupool_mask = cpupool_domain_cpumask(svc->vcpu->domain);
     cpumask_and(mask, cpupool_mask, svc->vcpu->cpu_hard_affinity);
     cpulist_scnprintf(keyhandler_scratch, sizeof(keyhandler_scratch), mask);
     printk("[%5d.%-2u] cpu %u, (%"PRI_stime", %"PRI_stime"),"
@@ -673,7 +673,7 @@ rt_cpu_pick(const struct scheduler *ops, struct vcpu *vc)
     cpumask_t *online;
     int cpu;
 
-    online = cpupool_scheduler_cpumask(vc->domain->cpupool);
+    online = cpupool_domain_cpumask(vc->domain);
     cpumask_and(&cpus, online, vc->cpu_hard_affinity);
 
     cpu = cpumask_test_cpu(vc->processor, &cpus)
@@ -753,7 +753,7 @@ __runq_pick(const struct scheduler *ops, const cpumask_t *mask)
         iter_svc = __q_elem(iter);
 
         /* mask cpu_hard_affinity & cpupool & mask */
-        online = cpupool_scheduler_cpumask(iter_svc->vcpu->domain->cpupool);
+        online = cpupool_domain_cpumask(iter_svc->vcpu->domain);
         cpumask_and(&cpu_common, online, iter_svc->vcpu->cpu_hard_affinity);
         cpumask_and(&cpu_common, mask, &cpu_common);
         if ( cpumask_empty(&cpu_common) )
@@ -965,7 +965,7 @@ runq_tickle(const struct scheduler *ops, struct rt_vcpu *new)
     if ( new == NULL || is_idle_vcpu(new->vcpu) )
         return;
 
-    online = cpupool_scheduler_cpumask(new->vcpu->domain->cpupool);
+    online = cpupool_domain_cpumask(new->vcpu->domain);
     cpumask_and(&not_tickled, online, new->vcpu->cpu_hard_affinity);
     cpumask_andnot(&not_tickled, &not_tickled, &prv->tickled);
 
@@ -1078,7 +1078,7 @@ rt_vcpu_wake(const struct scheduler *ops, struct vcpu *vc)
 
     ASSERT(!list_empty(&prv->sdom));
     sdom = list_entry(prv->sdom.next, struct rt_dom, sdom_elem);
-    online = cpupool_scheduler_cpumask(sdom->dom->cpupool);
+    online = cpupool_domain_cpumask(sdom->dom);
     snext = __runq_pick(ops, online); /* pick snext from ALL valid cpus */
 
     runq_tickle(ops, snext);
@@ -1113,7 +1113,7 @@ rt_context_saved(const struct scheduler *ops, struct vcpu *vc)
 
         ASSERT(!list_empty(&prv->sdom));
         sdom = list_entry(prv->sdom.next, struct rt_dom, sdom_elem);
-        online = cpupool_scheduler_cpumask(sdom->dom->cpupool);
+        online = cpupool_domain_cpumask(sdom->dom);
         snext = __runq_pick(ops, online); /* pick snext from ALL cpus */
 
         runq_tickle(ops, snext);
diff --git a/xen/common/schedule.c b/xen/common/schedule.c
index 3eefed7..5ffa1a1 100644
--- a/xen/common/schedule.c
+++ b/xen/common/schedule.c
@@ -79,7 +79,7 @@ static struct scheduler __read_mostly ops;
 
 #define DOM2OP(_d)    (((_d)->cpupool == NULL) ? &ops : ((_d)->cpupool->sched))
 #define VCPU2OP(_v)   (DOM2OP((_v)->domain))
-#define VCPU2ONLINE(_v) cpupool_online_cpumask((_v)->domain->cpupool)
+#define VCPU2ONLINE(_v) cpupool_domain_cpumask((_v)->domain)
 
 static inline void trace_runstate_change(struct vcpu *v, int new_state)
 {
diff --git a/xen/include/xen/sched-if.h b/xen/include/xen/sched-if.h
index dbe7cab..493d43f 100644
--- a/xen/include/xen/sched-if.h
+++ b/xen/include/xen/sched-if.h
@@ -182,9 +182,17 @@ struct cpupool
     atomic_t         refcnt;
 };
 
-#define cpupool_scheduler_cpumask(_pool) \
-    (((_pool) == NULL) ? &cpupool_free_cpus : (_pool)->cpu_valid)
 #define cpupool_online_cpumask(_pool) \
     (((_pool) == NULL) ? &cpu_online_map : (_pool)->cpu_valid)
 
+static inline cpumask_t* cpupool_domain_cpumask(struct domain *d)
+{
+    /*
+     * d->cpupool is NULL only for the idle domain, and no one should
+     * be interested in calling this for the idle domain.
+     */
+    ASSERT(d->cpupool != NULL);
+    return d->cpupool->cpu_valid;
+}
+
 #endif /* __XEN_SCHED_IF_H__ */

Re: [PATCH] xen: sched: get rid of cpupool_scheduler_cpumask()

[George Dunlap]

On 24/09/15 04:40, Dario Faggioli wrote:
> and of (almost every) direct use of cpupool_online_cpumask().
> 
> In fact, what we really want for the most of the times,
> is the set of valid pCPUs of the cpupool a certain domain
> is part of. Furthermore, in case it's called with a NULL
> pool as argument, cpupool_scheduler_cpumask() does more
> harm than good, by returning the bitmask of free pCPUs!
> 
> This commit, therefore:
>  * gets rid of cpupool_scheduler_cpumask(), in favour of
>    cpupool_domain_cpumask(), which makes it more evident
>    what we are after, and accommodates some sanity checking;
>  * replaces some of the calls to cpupool_online_cpumask()
>    with calls to the new functions too.
> 
> Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
> Acked-by: Juergen Gross <jgross@suse.com>
> Acked-by: Joshua Whitehead <josh.whitehead@dornerworks.com>
> Reviewed-by: Meng Xu <mengxu@cis.upenn.edu>

Right, sorry about not getting back to the new version.  Looks good:

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