From: Dario Faggioli <dario.faggioli@citrix.com>
To: xen-devel@lists.xenproject.org
Cc: George Dunlap <george.dunlap@eu.citrix.com>
Subject: [PATCH 15/16] xen: sched: scratch space for cpumasks on Credit2
Date: Fri, 18 Mar 2016 20:06:01 +0100 [thread overview]
Message-ID: <20160318190601.8117.67010.stgit@Solace.station> (raw)
In-Reply-To: <20160318185524.8117.74837.stgit@Solace.station>
like what's there already in both Credit1 and RTDS. In
fact, when playing with affinity, a lot of cpumask
manipulation is necessary, inside of various functions.
To avoid having a lot of cpumask_var_t on the stack,
this patch introduces a global scratch area.
Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
---
Cc: George Dunlap <george.dunlap@eu.citrix.com>
---
xen/common/sched_credit2.c | 50 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 50 insertions(+)
diff --git a/xen/common/sched_credit2.c b/xen/common/sched_credit2.c
index 07b8c67..a650216 100644
--- a/xen/common/sched_credit2.c
+++ b/xen/common/sched_credit2.c
@@ -238,6 +238,23 @@ static void parse_credit2_runqueue(const char *s)
custom_param("credit2_runqueue", parse_credit2_runqueue);
/*
+ * Scratch space, useful to avoid having too many cpumask_var_t on the stack.
+ *
+ * We want to only allocate the array the first time an instance of this
+ * scheduler is used, and avoid reallocating it (e.g., when more instances
+ * are activated inside new cpupools) or leaking it (e.g., when the last
+ * instance is de-inited).
+ *
+ * Counting the number of active Credit2 instances is all we need, and it
+ * does not even have to happen via atomic_t operations, as the counter
+ * only changes during during boot, or under the cpupool_lock.
+ */
+static cpumask_t **_cpumask_scratch;
+#define cpumask_scratch _cpumask_scratch[smp_processor_id()]
+
+static unsigned int nr_csched2_ops;
+
+/*
* Per-runqueue data
*/
struct csched2_runqueue_data {
@@ -2166,6 +2183,15 @@ csched2_switch_sched(struct scheduler *new_ops, unsigned int cpu,
spin_unlock_irq(&prv->lock);
}
+static void *
+csched2_alloc_pdata(const struct scheduler *ops, int cpu)
+{
+ if ( !zalloc_cpumask_var(&_cpumask_scratch[cpu]) )
+ return ERR_PTR(-ENOMEM);
+
+ return NULL;
+}
+
static void
csched2_free_pdata(const struct scheduler *ops, void *pcpu, int cpu)
{
@@ -2205,6 +2231,9 @@ csched2_free_pdata(const struct scheduler *ops, void *pcpu, int cpu)
spin_unlock_irqrestore(&prv->lock, flags);
+ free_cpumask_var(_cpumask_scratch[cpu]);
+ _cpumask_scratch[cpu] = NULL;
+
return;
}
@@ -2239,6 +2268,19 @@ csched2_init(struct scheduler *ops)
if ( prv == NULL )
return -ENOMEM;
ops->sched_data = prv;
+
+ ASSERT( _cpumask_scratch == NULL || nr_csched2_ops > 0 );
+ if ( !_cpumask_scratch )
+ {
+ _cpumask_scratch = xmalloc_array(cpumask_var_t, nr_cpu_ids);
+ if ( !_cpumask_scratch )
+ {
+ xfree(prv);
+ return -ENOMEM;
+ }
+ }
+ nr_csched2_ops++;
+
spin_lock_init(&prv->lock);
INIT_LIST_HEAD(&prv->sdom);
@@ -2259,6 +2301,13 @@ csched2_deinit(struct scheduler *ops)
{
struct csched2_private *prv;
+ ASSERT( _cpumask_scratch && nr_csched2_ops > 0 );
+ if ( (--nr_csched2_ops) == 0 )
+ {
+ xfree(_cpumask_scratch);
+ _cpumask_scratch = NULL;
+ }
+
prv = CSCHED2_PRIV(ops);
ops->sched_data = NULL;
xfree(prv);
@@ -2293,6 +2342,7 @@ static const struct scheduler sched_credit2_def = {
.alloc_vdata = csched2_alloc_vdata,
.free_vdata = csched2_free_vdata,
.init_pdata = csched2_init_pdata,
+ .alloc_pdata = csched2_alloc_pdata,
.free_pdata = csched2_free_pdata,
.switch_sched = csched2_switch_sched,
.alloc_domdata = csched2_alloc_domdata,
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next prev parent reply other threads:[~2016-03-18 19:06 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-18 19:03 [PATCH 00/16] Fixes and improvement (including hard affinity!) for Credit2 Dario Faggioli
2016-03-18 19:04 ` [PATCH 01/16] xen: sched: fix locking when allocating an RTDS pCPU Dario Faggioli
2016-03-19 2:22 ` Meng Xu
2016-03-23 15:37 ` George Dunlap
2016-03-18 19:04 ` [PATCH 02/16] xen: sched: add .init_pdata hook to the scheduler interface Dario Faggioli
2016-03-22 8:08 ` Juergen Gross
2016-03-23 17:32 ` George Dunlap
2016-03-18 19:04 ` [PATCH 03/16] xen: sched: make implementing .alloc_pdata optional Dario Faggioli
2016-03-19 2:23 ` Meng Xu
2016-03-21 14:22 ` Jan Beulich
2016-03-23 17:36 ` George Dunlap
2016-03-24 9:43 ` Jan Beulich
2016-03-24 13:14 ` Dario Faggioli
2016-03-21 14:48 ` Juergen Gross
2016-03-21 15:07 ` Jan Beulich
2016-04-01 17:01 ` Dario Faggioli
2016-04-04 4:21 ` Juergen Gross
2016-04-04 6:13 ` Jan Beulich
2016-04-05 16:01 ` Dario Faggioli
2016-03-23 17:38 ` George Dunlap
2016-03-18 19:04 ` [PATCH 04/16] xen: sched: implement .init_pdata in all schedulers Dario Faggioli
2016-03-19 2:24 ` Meng Xu
2016-03-22 8:03 ` Juergen Gross
2016-03-23 17:46 ` George Dunlap
2016-03-18 19:04 ` [PATCH 05/16] xen: sched: move pCPU initialization in an helper Dario Faggioli
2016-03-23 17:51 ` George Dunlap
2016-03-23 18:09 ` George Dunlap
2016-03-24 13:21 ` Dario Faggioli
2016-03-18 19:04 ` [PATCH 06/16] xen: sched: prepare a .switch_sched hook for Credit1 Dario Faggioli
2016-03-18 19:04 ` [PATCH 07/16] xen: sched: prepare a .switch_sched hook for Credit2 Dario Faggioli
2016-03-18 19:04 ` [PATCH 08/16] " Dario Faggioli
2016-03-19 2:24 ` Meng Xu
2016-03-21 14:25 ` Jan Beulich
2016-03-18 19:05 ` [PATCH 09/16] xen: sched: close potential races when switching scheduler to CPUs Dario Faggioli
2016-03-19 2:25 ` Meng Xu
2016-03-23 19:05 ` George Dunlap
2016-04-05 16:26 ` Dario Faggioli
2016-04-06 15:51 ` Dario Faggioli
2016-03-24 12:14 ` George Dunlap
2016-04-05 17:37 ` Dario Faggioli
2016-04-06 16:21 ` Dario Faggioli
2016-03-18 19:05 ` [PATCH 10/16] xen: sched: improve credit2 bootparams' scope, placement and signedness Dario Faggioli
2016-03-21 14:51 ` Juergen Gross
2016-03-24 12:20 ` George Dunlap
2016-03-18 19:05 ` [PATCH 11/16] xen: sched: on Credit2, don't reprogram the timer if idle Dario Faggioli
2016-03-24 15:03 ` George Dunlap
2016-03-18 19:05 ` [PATCH 12/16] xen: sched: fix per-socket runqueue creation in credit2 Dario Faggioli
2016-03-24 12:24 ` George Dunlap
2016-03-18 19:05 ` [PATCH 13/16] xen: sched: allow for choosing credit2 runqueues configuration at boot Dario Faggioli
2016-03-22 7:46 ` Juergen Gross
2016-03-24 12:36 ` George Dunlap
2016-03-18 19:05 ` [PATCH 14/16] xen: sched: per-core runqueues as default in credit2 Dario Faggioli
2016-03-24 12:37 ` George Dunlap
2016-03-18 19:06 ` Dario Faggioli [this message]
2016-03-18 19:27 ` [PATCH 15/16] xen: sched: scratch space for cpumasks on Credit2 Andrew Cooper
2016-03-24 12:44 ` George Dunlap
2016-03-24 12:56 ` Andrew Cooper
2016-03-24 13:10 ` Dario Faggioli
2016-03-18 19:06 ` [PATCH 16/16] xen: sched: implement vcpu hard affinity in Credit2 Dario Faggioli
2016-03-24 15:42 ` George Dunlap
2016-04-05 16:50 ` Dario Faggioli
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