| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20100428111717.7954.30963.stgit@kitami.corp.google.com>
Date: Wed, 28 Apr 2010 04:17:17 -0700
From: Paul Turner <pjt@...gle.com>
To: linux-kernel@...r.kernel.org
Cc: Paul Menage <menage@...gle.com>,
Srivatsa Vaddagiri <vatsa@...ibm.com>,
Dhaval Giani <dhaval@...ux.vnet.ibm.com>,
Gautham R Shenoy <ego@...ibm.com>,
Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>,
Herbert Poetzl <herbert@...hfloor.at>,
Balbir Singh <balbir@...ux.vnet.ibm.com>,
Chris Friesen <cfriesen@...tel.com>,
Avi Kivity <avi@...hat.com>,
Bharata B Rao <bharata@...ux.vnet.ibm.com>,
Nikhil Rao <ncrao@...gle.com>, Ingo Molnar <mingo@...e.hu>,
Pavel Emelyanov <xemul@...nvz.org>,
Mike Waychison <mikew@...gle.com>,
Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: [PATCH v2 6/6] sched: hierarchical task accounting for
FAIR_GROUP_SCHED
With task entities participating in throttled sub-trees it is possible for
task activation/de-activation to not lead to root visible changes to
rq->nr_running. This in turn leads to incorrect idle and weight-per-task load
balance decisions.
To allow correct accounting we move responsibility for updating rq->nr_running
to the respective sched::classes. In the fair-group case this update is
hierarchical, tracking the number of active tasks rooted at each group entity.
Note: technically this issue also exists with the existing sched_rt
throttling; however due to the nearly complete provisioning of system
resources for rt scheduling this is much less common by default.
---
kernel/sched.c | 9 ++++++---
kernel/sched_fair.c | 42 ++++++++++++++++++++++++++++++++++++++++++
kernel/sched_rt.c | 5 ++++-
3 files changed, 52 insertions(+), 4 deletions(-)
diff --git a/kernel/sched.c b/kernel/sched.c
index ac74d3a..87fb0c0 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -368,7 +368,7 @@ static inline struct task_group *task_group(struct task_struct *p)
/* CFS-related fields in a runqueue */
struct cfs_rq {
struct load_weight load;
- unsigned long nr_running;
+ unsigned long nr_running, h_nr_tasks;
u64 exec_clock;
u64 min_vruntime;
@@ -1967,6 +1967,11 @@ static inline u64 sched_cfs_bandwidth_slice(void)
#include "sched_stats.h"
+static void mod_nr_running(struct rq *rq, long delta)
+{
+ rq->nr_running += delta;
+}
+
static void inc_nr_running(struct rq *rq)
{
rq->nr_running++;
@@ -2042,7 +2047,6 @@ static void activate_task(struct rq *rq, struct task_struct *p, int wakeup)
rq->nr_uninterruptible--;
enqueue_task(rq, p, wakeup, false);
- inc_nr_running(rq);
}
/*
@@ -2054,7 +2058,6 @@ static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep)
rq->nr_uninterruptible++;
dequeue_task(rq, p, sleep);
- dec_nr_running(rq);
}
#include "sched_idletask.c"
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index edea44e..eb6ed15 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -76,6 +76,8 @@ unsigned int sysctl_sched_child_runs_first __read_mostly;
*/
unsigned int __read_mostly sysctl_sched_compat_yield;
+static void account_hier_tasks(struct sched_entity *se, int delta);
+
/*
* SCHED_OTHER wake-up granularity.
* (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds)
@@ -682,6 +684,40 @@ account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
se->on_rq = 0;
}
+#ifdef CONFIG_CFS_BANDWIDTH
+/* maintain hierarchal task counts on group entities */
+static void account_hier_tasks(struct sched_entity *se, int delta)
+{
+ struct rq *rq = rq_of(cfs_rq_of(se));
+ struct cfs_rq *cfs_rq;
+
+ for_each_sched_entity(se) {
+ /* a throttled entity cannot affect its parent hierarchy */
+ if (group_cfs_rq(se) && cfs_rq_throttled(group_cfs_rq(se)))
+ break;
+
+ /* we affect our queuing entity */
+ cfs_rq = cfs_rq_of(se);
+ cfs_rq->h_nr_tasks += delta;
+ }
+
+ /* account for global nr_running delta to hierarchy change */
+ if (!se)
+ mod_nr_running(rq, delta);
+}
+#else
+/*
+ * In the absence of group throttling, all operations are guaranteed to be
+ * globally visible at the root rq level.
+ */
+static void account_hier_tasks(struct sched_entity *se, int delta)
+{
+ struct rq *rq = rq_of(cfs_rq_of(se));
+
+ mod_nr_running(rq, delta);
+}
+#endif
+
static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
#ifdef CONFIG_SCHEDSTATS
@@ -1117,6 +1153,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int wakeup, bool head)
flags = ENQUEUE_WAKEUP;
}
+ account_hier_tasks(&p->se, 1);
hrtick_update(rq);
}
@@ -1142,6 +1179,7 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int sleep)
sleep = 1;
}
+ account_hier_tasks(&p->se, -1);
hrtick_update(rq);
}
@@ -1215,12 +1253,15 @@ static u64 tg_request_cfs_quota(struct task_group *tg)
return delta;
}
+static void account_hier_tasks(struct sched_entity *se, int delta);
+
static void throttle_cfs_rq(struct cfs_rq *cfs_rq)
{
struct sched_entity *se;
se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
+ account_hier_tasks(se, -cfs_rq->h_nr_tasks);
for_each_sched_entity(se) {
struct cfs_rq *cfs_rq = cfs_rq_of(se);
@@ -1249,6 +1290,7 @@ static void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
cfs_rq->throttled = 0;
cfs_rq->throttled_timestamp = 0;
+ account_hier_tasks(se, cfs_rq->h_nr_tasks);
for_each_sched_entity(se) {
if (se->on_rq)
break;
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 15bbc45..c908bc0 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -882,6 +882,8 @@ enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup, bool head)
if (!task_current(rq, p) && p->rt.nr_cpus_allowed > 1)
enqueue_pushable_task(rq, p);
+
+ inc_nr_running(rq);
}
static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep)
@@ -892,6 +894,8 @@ static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep)
dequeue_rt_entity(rt_se);
dequeue_pushable_task(rq, p);
+
+ dec_nr_running(rq);
}
/*
@@ -1758,4 +1762,3 @@ static void print_rt_stats(struct seq_file *m, int cpu)
rcu_read_unlock();
}
#endif /* CONFIG_SCHED_DEBUG */
-
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists