Merge tag 'sched-psi-2022-10-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull PSI updates from Ingo Molnar:

 - Various performance optimizations, resulting in a 4%-9% speedup in
   the mmtests/config-scheduler-perfpipe micro-benchmark.

 - New interface to turn PSI on/off on a per cgroup level.

* tag 'sched-psi-2022-10-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/psi: Per-cgroup PSI accounting disable/re-enable interface
  sched/psi: Cache parent psi_group to speed up group iteration
  sched/psi: Consolidate cgroup_psi()
  sched/psi: Add PSI_IRQ to track IRQ/SOFTIRQ pressure
  sched/psi: Remove NR_ONCPU task accounting
  sched/psi: Optimize task switch inside shared cgroups again
  sched/psi: Move private helpers to sched/stats.h
  sched/psi: Save percpu memory when !psi_cgroups_enabled
  sched/psi: Don't create cgroup PSI files when psi_disabled
  sched/psi: Fix periodic aggregation shut off

1 files changed, 95 insertions, 9 deletions

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 764bdd5fd8d1..7f486677ab1f 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -3698,27 +3698,27 @@ static int cpu_stat_show(struct seq_file *seq, void *v)
 static int cgroup_io_pressure_show(struct seq_file *seq, void *v)
 {
 	struct cgroup *cgrp = seq_css(seq)->cgroup;
-	struct psi_group *psi = cgroup_ino(cgrp) == 1 ? &psi_system : cgrp->psi;
+	struct psi_group *psi = cgroup_psi(cgrp);
 
 	return psi_show(seq, psi, PSI_IO);
 }
 static int cgroup_memory_pressure_show(struct seq_file *seq, void *v)
 {
 	struct cgroup *cgrp = seq_css(seq)->cgroup;
-	struct psi_group *psi = cgroup_ino(cgrp) == 1 ? &psi_system : cgrp->psi;
+	struct psi_group *psi = cgroup_psi(cgrp);
 
 	return psi_show(seq, psi, PSI_MEM);
 }
 static int cgroup_cpu_pressure_show(struct seq_file *seq, void *v)
 {
 	struct cgroup *cgrp = seq_css(seq)->cgroup;
-	struct psi_group *psi = cgroup_ino(cgrp) == 1 ? &psi_system : cgrp->psi;
+	struct psi_group *psi = cgroup_psi(cgrp);
 
 	return psi_show(seq, psi, PSI_CPU);
 }
 
-static ssize_t cgroup_pressure_write(struct kernfs_open_file *of, char *buf,
-					  size_t nbytes, enum psi_res res)
+static ssize_t pressure_write(struct kernfs_open_file *of, char *buf,
+			      size_t nbytes, enum psi_res res)
 {
 	struct cgroup_file_ctx *ctx = of->priv;
 	struct psi_trigger *new;
@@ -3738,7 +3738,7 @@ static ssize_t cgroup_pressure_write(struct kernfs_open_file *of, char *buf,
 		return -EBUSY;
 	}
 
-	psi = cgroup_ino(cgrp) == 1 ? &psi_system : cgrp->psi;
+	psi = cgroup_psi(cgrp);
 	new = psi_trigger_create(psi, buf, res);
 	if (IS_ERR(new)) {
 		cgroup_put(cgrp);
@@ -3755,21 +3755,86 @@ static ssize_t cgroup_io_pressure_write(struct kernfs_open_file *of,
 					  char *buf, size_t nbytes,
 					  loff_t off)
 {
-	return cgroup_pressure_write(of, buf, nbytes, PSI_IO);
+	return pressure_write(of, buf, nbytes, PSI_IO);
 }
 
 static ssize_t cgroup_memory_pressure_write(struct kernfs_open_file *of,
 					  char *buf, size_t nbytes,
 					  loff_t off)
 {
-	return cgroup_pressure_write(of, buf, nbytes, PSI_MEM);
+	return pressure_write(of, buf, nbytes, PSI_MEM);
 }
 
 static ssize_t cgroup_cpu_pressure_write(struct kernfs_open_file *of,
 					  char *buf, size_t nbytes,
 					  loff_t off)
 {
-	return cgroup_pressure_write(of, buf, nbytes, PSI_CPU);
+	return pressure_write(of, buf, nbytes, PSI_CPU);
+}
+
+#ifdef CONFIG_IRQ_TIME_ACCOUNTING
+static int cgroup_irq_pressure_show(struct seq_file *seq, void *v)
+{
+	struct cgroup *cgrp = seq_css(seq)->cgroup;
+	struct psi_group *psi = cgroup_psi(cgrp);
+
+	return psi_show(seq, psi, PSI_IRQ);
+}
+
+static ssize_t cgroup_irq_pressure_write(struct kernfs_open_file *of,
+					 char *buf, size_t nbytes,
+					 loff_t off)
+{
+	return pressure_write(of, buf, nbytes, PSI_IRQ);
+}
+#endif
+
+static int cgroup_pressure_show(struct seq_file *seq, void *v)
+{
+	struct cgroup *cgrp = seq_css(seq)->cgroup;
+	struct psi_group *psi = cgroup_psi(cgrp);
+
+	seq_printf(seq, "%d\n", psi->enabled);
+
+	return 0;
+}
+
+static ssize_t cgroup_pressure_write(struct kernfs_open_file *of,
+				     char *buf, size_t nbytes,
+				     loff_t off)
+{
+	ssize_t ret;
+	int enable;
+	struct cgroup *cgrp;
+	struct psi_group *psi;
+
+	ret = kstrtoint(strstrip(buf), 0, &enable);
+	if (ret)
+		return ret;
+
+	if (enable < 0 || enable > 1)
+		return -ERANGE;
+
+	cgrp = cgroup_kn_lock_live(of->kn, false);
+	if (!cgrp)
+		return -ENOENT;
+
+	psi = cgroup_psi(cgrp);
+	if (psi->enabled != enable) {
+		int i;
+
+		/* show or hide {cpu,memory,io,irq}.pressure files */
+		for (i = 0; i < NR_PSI_RESOURCES; i++)
+			cgroup_file_show(&cgrp->psi_files[i], enable);
+
+		psi->enabled = enable;
+		if (enable)
+			psi_cgroup_restart(psi);
+	}
+
+	cgroup_kn_unlock(of->kn);
+
+	return nbytes;
 }
 
 static __poll_t cgroup_pressure_poll(struct kernfs_open_file *of,
@@ -3789,6 +3854,9 @@ static void cgroup_pressure_release(struct kernfs_open_file *of)
 
 bool cgroup_psi_enabled(void)
 {
+	if (static_branch_likely(&psi_disabled))
+		return false;
+
 	return (cgroup_feature_disable_mask & (1 << OPT_FEATURE_PRESSURE)) == 0;
 }
 
@@ -5175,6 +5243,7 @@ static struct cftype cgroup_psi_files[] = {
 #ifdef CONFIG_PSI
 	{
 		.name = "io.pressure",
+		.file_offset = offsetof(struct cgroup, psi_files[PSI_IO]),
 		.seq_show = cgroup_io_pressure_show,
 		.write = cgroup_io_pressure_write,
 		.poll = cgroup_pressure_poll,
@@ -5182,6 +5251,7 @@ static struct cftype cgroup_psi_files[] = {
 	},
 	{
 		.name = "memory.pressure",
+		.file_offset = offsetof(struct cgroup, psi_files[PSI_MEM]),
 		.seq_show = cgroup_memory_pressure_show,
 		.write = cgroup_memory_pressure_write,
 		.poll = cgroup_pressure_poll,
@@ -5189,11 +5259,27 @@ static struct cftype cgroup_psi_files[] = {
 	},
 	{
 		.name = "cpu.pressure",
+		.file_offset = offsetof(struct cgroup, psi_files[PSI_CPU]),
 		.seq_show = cgroup_cpu_pressure_show,
 		.write = cgroup_cpu_pressure_write,
 		.poll = cgroup_pressure_poll,
 		.release = cgroup_pressure_release,
 	},
+#ifdef CONFIG_IRQ_TIME_ACCOUNTING
+	{
+		.name = "irq.pressure",
+		.file_offset = offsetof(struct cgroup, psi_files[PSI_IRQ]),
+		.seq_show = cgroup_irq_pressure_show,
+		.write = cgroup_irq_pressure_write,
+		.poll = cgroup_pressure_poll,
+		.release = cgroup_pressure_release,
+	},
+#endif
+	{
+		.name = "cgroup.pressure",
+		.seq_show = cgroup_pressure_show,
+		.write = cgroup_pressure_write,
+	},
 #endif /* CONFIG_PSI */
 	{ }	/* terminate */
 };