The patch titled
Subject: psi: cgroup support
has been added to the -mm tree. Its filename is
psi-cgroup-support.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/psi-cgroup-support.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/psi-cgroup-support.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Johannes Weiner <hannes@xxxxxxxxxxx>
Subject: psi: cgroup support
On a system that executes multiple cgrouped jobs and independent
workloads, we don't just care about the health of the overall system, but
also that of individual jobs, so that we can ensure individual job health,
fairness between jobs, or prioritize some jobs over others.
This patch implements pressure stall tracking for cgroups. In kernels
with CONFIG_PSI=y, cgroup2 groups will have cpu.pressure, memory.pressure,
and io.pressure files that track aggregate pressure stall times for only
the tasks inside the cgroup.
Link: http://lkml.kernel.org/r/20180828172258.3185-10-hannes@xxxxxxxxxxx
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: Tejun Heo <tj@xxxxxxxxxx>
Tested-by: Daniel Drake <drake@xxxxxxxxxxxx>
Tested-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Christopher Lameter <cl@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Johannes Weiner <jweiner@xxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Peter Enderborg <peter.enderborg@xxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Vinayak Menon <vinmenon@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/accounting/psi.txt | 9 +
Documentation/admin-guide/cgroup-v2.rst | 18 +++
include/linux/cgroup-defs.h | 4
include/linux/cgroup.h | 15 ++
include/linux/psi.h | 25 ++++
init/Kconfig | 4
kernel/cgroup/cgroup.c | 45 ++++++++
kernel/sched/psi.c | 118 ++++++++++++++++++++--
8 files changed, 228 insertions(+), 10 deletions(-)
--- a/Documentation/accounting/psi.txt~psi-cgroup-support
+++ a/Documentation/accounting/psi.txt
@@ -62,3 +62,12 @@ well as medium and long term trends. The
tracked and exported as well, to allow detection of latency spikes
which wouldn't necessarily make a dent in the time averages, or to
average trends over custom time frames.
+
+Cgroup2 interface
+=================
+
+In a system with a CONFIG_CGROUP=y kernel and the cgroup2 filesystem
+mounted, pressure stall information is also tracked for tasks grouped
+into cgroups. Each subdirectory in the cgroupfs mountpoint contains
+cpu.pressure, memory.pressure, and io.pressure files; the format is
+the same as the /proc/pressure/ files.
--- a/Documentation/admin-guide/cgroup-v2.rst~psi-cgroup-support
+++ a/Documentation/admin-guide/cgroup-v2.rst
@@ -966,6 +966,12 @@ All time durations are in microseconds.
$PERIOD duration. "max" for $MAX indicates no limit. If only
one number is written, $MAX is updated.
+ cpu.pressure
+ A read-only nested-key file which exists on non-root cgroups.
+
+ Shows pressure stall information for CPU. See
+ Documentation/accounting/psi.txt for details.
+
Memory
------
@@ -1271,6 +1277,12 @@ PAGE_SIZE multiple when read back.
higher than the limit for an extended period of time. This
reduces the impact on the workload and memory management.
+ memory.pressure
+ A read-only nested-key file which exists on non-root cgroups.
+
+ Shows pressure stall information for memory. See
+ Documentation/accounting/psi.txt for details.
+
Usage Guidelines
~~~~~~~~~~~~~~~~
@@ -1408,6 +1420,12 @@ IO Interface Files
8:16 rbps=2097152 wbps=max riops=max wiops=max
+ io.pressure
+ A read-only nested-key file which exists on non-root cgroups.
+
+ Shows pressure stall information for IO. See
+ Documentation/accounting/psi.txt for details.
+
Writeback
~~~~~~~~~
--- a/include/linux/cgroup-defs.h~psi-cgroup-support
+++ a/include/linux/cgroup-defs.h
@@ -20,6 +20,7 @@
#include <linux/u64_stats_sync.h>
#include <linux/workqueue.h>
#include <linux/bpf-cgroup.h>
+#include <linux/psi_types.h>
#ifdef CONFIG_CGROUPS
@@ -435,6 +436,9 @@ struct cgroup {
/* used to schedule release agent */
struct work_struct release_agent_work;
+ /* used to track pressure stalls */
+ struct psi_group psi;
+
/* used to store eBPF programs */
struct cgroup_bpf bpf;
--- a/include/linux/cgroup.h~psi-cgroup-support
+++ a/include/linux/cgroup.h
@@ -657,6 +657,11 @@ static inline void pr_cont_cgroup_path(s
pr_cont_kernfs_path(cgrp->kn);
}
+static inline struct psi_group *cgroup_psi(struct cgroup *cgrp)
+{
+ return &cgrp->psi;
+}
+
static inline void cgroup_init_kthreadd(void)
{
/*
@@ -709,6 +714,16 @@ static inline union kernfs_node_id *cgro
{
return NULL;
}
+
+static inline struct cgroup *cgroup_parent(struct cgroup *cgrp)
+{
+ return NULL;
+}
+
+static inline struct psi_group *cgroup_psi(struct cgroup *cgrp)
+{
+ return NULL;
+}
static inline bool task_under_cgroup_hierarchy(struct task_struct *task,
struct cgroup *ancestor)
--- a/include/linux/psi.h~psi-cgroup-support
+++ a/include/linux/psi.h
@@ -4,6 +4,9 @@
#include <linux/psi_types.h>
#include <linux/sched.h>
+struct seq_file;
+struct css_set;
+
#ifdef CONFIG_PSI
extern bool psi_disabled;
@@ -16,6 +19,14 @@ void psi_memstall_tick(struct task_struc
void psi_memstall_enter(unsigned long *flags);
void psi_memstall_leave(unsigned long *flags);
+int psi_show(struct seq_file *s, struct psi_group *group, enum psi_res res);
+
+#ifdef CONFIG_CGROUPS
+int psi_cgroup_alloc(struct cgroup *cgrp);
+void psi_cgroup_free(struct cgroup *cgrp);
+void cgroup_move_task(struct task_struct *p, struct css_set *to);
+#endif
+
#else /* CONFIG_PSI */
static inline void psi_init(void) {}
@@ -23,6 +34,20 @@ static inline void psi_init(void) {}
static inline void psi_memstall_enter(unsigned long *flags) {}
static inline void psi_memstall_leave(unsigned long *flags) {}
+#ifdef CONFIG_CGROUPS
+static inline int psi_cgroup_alloc(struct cgroup *cgrp)
+{
+ return 0;
+}
+static inline void psi_cgroup_free(struct cgroup *cgrp)
+{
+}
+static inline void cgroup_move_task(struct task_struct *p, struct css_set *to)
+{
+ rcu_assign_pointer(p->cgroups, to);
+}
+#endif
+
#endif /* CONFIG_PSI */
#endif /* _LINUX_PSI_H */
--- a/init/Kconfig~psi-cgroup-support
+++ a/init/Kconfig
@@ -496,6 +496,10 @@ config PSI
the share of walltime in which some or all tasks in the system are
delayed due to contention of the respective resource.
+ In kernels with cgroup support, cgroups (cgroup2 only) will
+ have cpu.pressure, memory.pressure, and io.pressure files,
+ which aggregate pressure stalls for the grouped tasks only.
+
For more details see Documentation/accounting/psi.txt.
Say N if unsure.
--- a/kernel/cgroup/cgroup.c~psi-cgroup-support
+++ a/kernel/cgroup/cgroup.c
@@ -55,6 +55,7 @@
#include <linux/nsproxy.h>
#include <linux/file.h>
#include <linux/sched/cputime.h>
+#include <linux/psi.h>
#include <net/sock.h>
#define CREATE_TRACE_POINTS
@@ -832,7 +833,7 @@ static void css_set_move_task(struct tas
*/
WARN_ON_ONCE(task->flags & PF_EXITING);
- rcu_assign_pointer(task->cgroups, to_cset);
+ cgroup_move_task(task, to_cset);
list_add_tail(&task->cg_list, use_mg_tasks ? &to_cset->mg_tasks :
&to_cset->tasks);
}
@@ -3409,6 +3410,21 @@ static int cpu_stat_show(struct seq_file
return ret;
}
+#ifdef CONFIG_PSI
+static int cgroup_io_pressure_show(struct seq_file *seq, void *v)
+{
+ return psi_show(seq, &seq_css(seq)->cgroup->psi, PSI_IO);
+}
+static int cgroup_memory_pressure_show(struct seq_file *seq, void *v)
+{
+ return psi_show(seq, &seq_css(seq)->cgroup->psi, PSI_MEM);
+}
+static int cgroup_cpu_pressure_show(struct seq_file *seq, void *v)
+{
+ return psi_show(seq, &seq_css(seq)->cgroup->psi, PSI_CPU);
+}
+#endif
+
static int cgroup_file_open(struct kernfs_open_file *of)
{
struct cftype *cft = of->kn->priv;
@@ -4539,6 +4555,23 @@ static struct cftype cgroup_base_files[]
.flags = CFTYPE_NOT_ON_ROOT,
.seq_show = cpu_stat_show,
},
+#ifdef CONFIG_PSI
+ {
+ .name = "io.pressure",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .seq_show = cgroup_io_pressure_show,
+ },
+ {
+ .name = "memory.pressure",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .seq_show = cgroup_memory_pressure_show,
+ },
+ {
+ .name = "cpu.pressure",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .seq_show = cgroup_cpu_pressure_show,
+ },
+#endif
{ } /* terminate */
};
@@ -4599,6 +4632,7 @@ static void css_free_rwork_fn(struct wor
*/
cgroup_put(cgroup_parent(cgrp));
kernfs_put(cgrp->kn);
+ psi_cgroup_free(cgrp);
if (cgroup_on_dfl(cgrp))
cgroup_rstat_exit(cgrp);
kfree(cgrp);
@@ -4855,10 +4889,15 @@ static struct cgroup *cgroup_create(stru
cgrp->self.parent = &parent->self;
cgrp->root = root;
cgrp->level = level;
- ret = cgroup_bpf_inherit(cgrp);
+
+ ret = psi_cgroup_alloc(cgrp);
if (ret)
goto out_idr_free;
+ ret = cgroup_bpf_inherit(cgrp);
+ if (ret)
+ goto out_psi_free;
+
for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp)) {
cgrp->ancestor_ids[tcgrp->level] = tcgrp->id;
@@ -4896,6 +4935,8 @@ static struct cgroup *cgroup_create(stru
return cgrp;
+out_psi_free:
+ psi_cgroup_free(cgrp);
out_idr_free:
cgroup_idr_remove(&root->cgroup_idr, cgrp->id);
out_stat_exit:
--- a/kernel/sched/psi.c~psi-cgroup-support
+++ a/kernel/sched/psi.c
@@ -473,9 +473,35 @@ static void psi_group_change(struct psi_
schedule_delayed_work(&group->clock_work, PSI_FREQ);
}
+static struct psi_group *iterate_groups(struct task_struct *task, void **iter)
+{
+#ifdef CONFIG_CGROUPS
+ struct cgroup *cgroup = NULL;
+
+ if (!*iter)
+ cgroup = task->cgroups->dfl_cgrp;
+ else if (*iter == &psi_system)
+ return NULL;
+ else
+ cgroup = cgroup_parent(*iter);
+
+ if (cgroup && cgroup_parent(cgroup)) {
+ *iter = cgroup;
+ return cgroup_psi(cgroup);
+ }
+#else
+ if (*iter)
+ return NULL;
+#endif
+ *iter = &psi_system;
+ return &psi_system;
+}
+
void psi_task_change(struct task_struct *task, int clear, int set)
{
int cpu = task_cpu(task);
+ struct psi_group *group;
+ void *iter = NULL;
if (!task->pid)
return;
@@ -492,17 +518,23 @@ void psi_task_change(struct task_struct
task->psi_flags &= ~clear;
task->psi_flags |= set;
- psi_group_change(&psi_system, cpu, clear, set);
+ while ((group = iterate_groups(task, &iter)))
+ psi_group_change(group, cpu, clear, set);
}
void psi_memstall_tick(struct task_struct *task, int cpu)
{
- struct psi_group_cpu *groupc;
+ struct psi_group *group;
+ void *iter = NULL;
- groupc = per_cpu_ptr(psi_system.pcpu, cpu);
- write_seqcount_begin(&groupc->seq);
- record_times(groupc, cpu, true);
- write_seqcount_end(&groupc->seq);
+ while ((group = iterate_groups(task, &iter))) {
+ struct psi_group_cpu *groupc;
+
+ groupc = per_cpu_ptr(group->pcpu, cpu);
+ write_seqcount_begin(&groupc->seq);
+ record_times(groupc, cpu, true);
+ write_seqcount_end(&groupc->seq);
+ }
}
/**
@@ -565,8 +597,78 @@ void psi_memstall_leave(unsigned long *f
rq_unlock_irq(rq, &rf);
}
-static int psi_show(struct seq_file *m, struct psi_group *group,
- enum psi_res res)
+#ifdef CONFIG_CGROUPS
+int psi_cgroup_alloc(struct cgroup *cgroup)
+{
+ if (psi_disabled)
+ return 0;
+
+ cgroup->psi.pcpu = alloc_percpu(struct psi_group_cpu);
+ if (!cgroup->psi.pcpu)
+ return -ENOMEM;
+ group_init(&cgroup->psi);
+ return 0;
+}
+
+void psi_cgroup_free(struct cgroup *cgroup)
+{
+ if (psi_disabled)
+ return;
+
+ cancel_delayed_work_sync(&cgroup->psi.clock_work);
+ free_percpu(cgroup->psi.pcpu);
+}
+
+/**
+ * cgroup_move_task - move task to a different cgroup
+ * @task: the task
+ * @to: the target css_set
+ *
+ * Move task to a new cgroup and safely migrate its associated stall
+ * state between the different groups.
+ *
+ * This function acquires the task's rq lock to lock out concurrent
+ * changes to the task's scheduling state and - in case the task is
+ * running - concurrent changes to its stall state.
+ */
+void cgroup_move_task(struct task_struct *task, struct css_set *to)
+{
+ bool move_psi = !psi_disabled;
+ unsigned int task_flags = 0;
+ struct rq_flags rf;
+ struct rq *rq;
+
+ if (move_psi) {
+ rq = task_rq_lock(task, &rf);
+
+ if (task_on_rq_queued(task))
+ task_flags = TSK_RUNNING;
+ else if (task->in_iowait)
+ task_flags = TSK_IOWAIT;
+
+ if (task->flags & PF_MEMSTALL)
+ task_flags |= TSK_MEMSTALL;
+
+ if (task_flags)
+ psi_task_change(task, task_flags, 0);
+ }
+
+ /*
+ * Lame to do this here, but the scheduler cannot be locked
+ * from the outside, so we move cgroups from inside sched/.
+ */
+ rcu_assign_pointer(task->cgroups, to);
+
+ if (move_psi) {
+ if (task_flags)
+ psi_task_change(task, 0, task_flags);
+
+ task_rq_unlock(rq, task, &rf);
+ }
+}
+#endif /* CONFIG_CGROUPS */
+
+int psi_show(struct seq_file *m, struct psi_group *group, enum psi_res res)
{
int full;
_
Patches currently in -mm which might be from hannes@xxxxxxxxxxx are
mm-workingset-tell-cache-transitions-from-workingset-thrashing.patch
delayacct-track-delays-from-thrashing-cache-pages.patch
sched-loadavg-consolidate-load_int-load_frac-calc_load.patch
sched-loadavg-make-calc_load_n-public.patch
sched-schedh-make-rq-locking-and-clock-functions-available-in-statsh.patch
sched-introduce-this_rq_lock_irq.patch
psi-pressure-stall-information-for-cpu-memory-and-io.patch
psi-pressure-stall-information-for-cpu-memory-and-io-fix.patch
psi-pressure-stall-information-for-cpu-memory-and-io-fix-2.patch
psi-pressure-stall-information-for-cpu-memory-and-io-fix-3.patch
psi-cgroup-support.patch
