Merge "ANDROID: gki_config: disable per-cgroup pressure tracking"

Documentation/admin-guide/kernel-parameters.txt

@@ -488,16 +488,21 @@
 	ccw_timeout_log	[S390]
 			See Documentation/s390/common_io.rst for details.
 
-	cgroup_disable=	[KNL] Disable a particular controller
-			Format: {name of the controller(s) to disable}
+	cgroup_disable=	[KNL] Disable a particular controller or optional feature
+			Format: {name of the controller(s) or feature(s) to disable}
 			The effects of cgroup_disable=foo are:
 			- foo isn't auto-mounted if you mount all cgroups in
 			  a single hierarchy
 			- foo isn't visible as an individually mountable
 			  subsystem
+			- if foo is an optional feature then the feature is
+			  disabled and corresponding cgroup files are not
+			  created
 			{Currently only "memory" controller deal with this and
 			cut the overhead, others just disable the usage. So
 			only cgroup_disable=memory is actually worthy}
+			Specifying "pressure" disables per-cgroup pressure
+			stall information accounting feature
 
 	cgroup_no_v1=	[KNL] Disable cgroup controllers and named hierarchies in v1
 			Format: { { controller | "all" | "named" }

arch/arm64/configs/gki_defconfig

@@ -59,6 +59,8 @@ CONFIG_SWP_EMULATION=y
 CONFIG_CP15_BARRIER_EMULATION=y
 CONFIG_SETEND_EMULATION=y
 CONFIG_RANDOMIZE_BASE=y
+CONFIG_CMDLINE="cgroup_disable=pressure"
+CONFIG_CMDLINE_EXTEND=y
 # CONFIG_DMI is not set
 CONFIG_PM_WAKELOCKS=y
 CONFIG_PM_WAKELOCKS_LIMIT=0

arch/x86/configs/gki_defconfig

@@ -53,6 +53,8 @@ CONFIG_HYPERVISOR_GUEST=y
 CONFIG_PARAVIRT=y
 CONFIG_NR_CPUS=32
 CONFIG_EFI=y
+CONFIG_CMDLINE_BOOL=y
+CONFIG_CMDLINE="cgroup_disable=pressure"
 CONFIG_PM_WAKELOCKS=y
 CONFIG_PM_WAKELOCKS_LIMIT=0
 # CONFIG_PM_WAKELOCKS_GC is not set

include/linux/cgroup-defs.h

@@ -105,6 +105,7 @@ enum {
 	CFTYPE_NO_PREFIX	= (1 << 3),	/* (DON'T USE FOR NEW FILES) no subsys prefix */
 	CFTYPE_WORLD_WRITABLE	= (1 << 4),	/* (DON'T USE FOR NEW FILES) S_IWUGO */
 	CFTYPE_DEBUG		= (1 << 5),	/* create when cgroup_debug */
+	CFTYPE_PRESSURE		= (1 << 6),	/* only if pressure feature is enabled */
 
 	/* internal flags, do not use outside cgroup core proper */
 	__CFTYPE_ONLY_ON_DFL	= (1 << 16),	/* only on default hierarchy */

include/linux/cgroup.h

@@ -670,6 +670,8 @@ static inline struct psi_group *cgroup_psi(struct cgroup *cgrp)
 	return &cgrp->psi;
 }
 
+bool cgroup_psi_enabled(void);
+
 static inline void cgroup_init_kthreadd(void)
 {
 	/*
@@ -735,6 +737,11 @@ static inline struct psi_group *cgroup_psi(struct cgroup *cgrp)
 	return NULL;
 }
 
+static inline bool cgroup_psi_enabled(void)
+{
+	return false;
+}
+
 static inline bool task_under_cgroup_hierarchy(struct task_struct *task,
 					       struct cgroup *ancestor)
 {

kernel/cgroup/cgroup.c

@@ -213,6 +213,22 @@ struct cgroup_namespace init_cgroup_ns = {
 static struct file_system_type cgroup2_fs_type;
 static struct cftype cgroup_base_files[];
 
+/* cgroup optional features */
+enum cgroup_opt_features {
+#ifdef CONFIG_PSI
+	OPT_FEATURE_PRESSURE,
+#endif
+	OPT_FEATURE_COUNT
+};
+
+static const char *cgroup_opt_feature_names[OPT_FEATURE_COUNT] = {
+#ifdef CONFIG_PSI
+	"pressure",
+#endif
+};
+
+static u16 cgroup_feature_disable_mask __read_mostly;
+
 static int cgroup_apply_control(struct cgroup *cgrp);
 static void cgroup_finalize_control(struct cgroup *cgrp, int ret);
 static void css_task_iter_skip(struct css_task_iter *it,
@@ -3679,6 +3695,18 @@ static void cgroup_pressure_release(struct kernfs_open_file *of)
 {
 	psi_trigger_replace(&of->priv, NULL);
 }
+
+bool cgroup_psi_enabled(void)
+{
+	return (cgroup_feature_disable_mask & (1 << OPT_FEATURE_PRESSURE)) == 0;
+}
+
+#else /* CONFIG_PSI */
+bool cgroup_psi_enabled(void)
+{
+	return false;
+}
+
 #endif /* CONFIG_PSI */
 
 static int cgroup_freeze_show(struct seq_file *seq, void *v)
@@ -3926,6 +3954,8 @@ static int cgroup_addrm_files(struct cgroup_subsys_state *css,
 restart:
 	for (cft = cfts; cft != cft_end && cft->name[0] != '\0'; cft++) {
 		/* does cft->flags tell us to skip this file on @cgrp? */
+		if ((cft->flags & CFTYPE_PRESSURE) && !cgroup_psi_enabled())
+			continue;
 		if ((cft->flags & __CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp))
 			continue;
 		if ((cft->flags & __CFTYPE_NOT_ON_DFL) && cgroup_on_dfl(cgrp))
@@ -4003,6 +4033,9 @@ static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
 
 		WARN_ON(cft->ss || cft->kf_ops);
 
+		if ((cft->flags & CFTYPE_PRESSURE) && !cgroup_psi_enabled())
+			continue;
+
 		if (cft->seq_start)
 			kf_ops = &cgroup_kf_ops;
 		else
@@ -4919,6 +4952,7 @@ static struct cftype cgroup_base_files[] = {
 #ifdef CONFIG_PSI
 	{
 		.name = "io.pressure",
+		.flags = CFTYPE_PRESSURE,
 		.seq_show = cgroup_io_pressure_show,
 		.write = cgroup_io_pressure_write,
 		.poll = cgroup_pressure_poll,
@@ -4926,6 +4960,7 @@ static struct cftype cgroup_base_files[] = {
 	},
 	{
 		.name = "memory.pressure",
+		.flags = CFTYPE_PRESSURE,
 		.seq_show = cgroup_memory_pressure_show,
 		.write = cgroup_memory_pressure_write,
 		.poll = cgroup_pressure_poll,
@@ -4933,6 +4968,7 @@ static struct cftype cgroup_base_files[] = {
 	},
 	{
 		.name = "cpu.pressure",
+		.flags = CFTYPE_PRESSURE,
 		.seq_show = cgroup_cpu_pressure_show,
 		.write = cgroup_cpu_pressure_write,
 		.poll = cgroup_pressure_poll,
@@ -6173,6 +6209,15 @@ static int __init cgroup_disable(char *str)
 				continue;
 			cgroup_disable_mask |= 1 << i;
 		}
+
+		for (i = 0; i < OPT_FEATURE_COUNT; i++) {
+			if (strcmp(token, cgroup_opt_feature_names[i]))
+				continue;
+			cgroup_feature_disable_mask |= 1 << i;
+			pr_info("Disabling %s control group feature\n",
+				cgroup_opt_feature_names[i]);
+			break;
+		}
 	}
 	return 1;
 }
@@ -6476,6 +6521,9 @@ static ssize_t show_delegatable_files(struct cftype *files, char *buf,
 		if (!(cft->flags & CFTYPE_NS_DELEGATABLE))
 			continue;
 
+		if ((cft->flags & CFTYPE_PRESSURE) && !cgroup_psi_enabled())
+			continue;
+
 		if (prefix)
 			ret += snprintf(buf + ret, size - ret, "%s.", prefix);
 

kernel/sched/psi.c

@@ -148,6 +148,7 @@
 static int psi_bug __read_mostly;
 
 DEFINE_STATIC_KEY_FALSE(psi_disabled);
+DEFINE_STATIC_KEY_TRUE(psi_cgroups_enabled);
 
 #ifdef CONFIG_PSI_DEFAULT_DISABLED
 static bool psi_enable;
@@ -212,6 +213,9 @@ void __init psi_init(void)
 		return;
 	}
 
+	if (!cgroup_psi_enabled())
+		static_branch_disable(&psi_cgroups_enabled);
+
 	psi_period = jiffies_to_nsecs(PSI_FREQ);
 	group_init(&psi_system);
 }
@@ -763,23 +767,23 @@ static u32 psi_group_change(struct psi_group *group, int cpu,
 
 static struct psi_group *iterate_groups(struct task_struct *task, void **iter)
 {
+	if (*iter == &psi_system)
+		return NULL;
+
 #ifdef CONFIG_CGROUPS
-	struct cgroup *cgroup = NULL;
+	if (static_branch_likely(&psi_cgroups_enabled)) {
+		struct cgroup *cgroup = NULL;
 
-	if (!*iter)
-		cgroup = task->cgroups->dfl_cgrp;
-	else if (*iter == &psi_system)
-		return NULL;
-	else
-		cgroup = cgroup_parent(*iter);
+		if (!*iter)
+			cgroup = task->cgroups->dfl_cgrp;
+		else
+			cgroup = cgroup_parent(*iter);
 
-	if (cgroup && cgroup_parent(cgroup)) {
-		*iter = cgroup;
-		return cgroup_psi(cgroup);
+		if (cgroup && cgroup_parent(cgroup)) {
+			*iter = cgroup;
+			return cgroup_psi(cgroup);
+		}
 	}
-#else
-	if (*iter)
-		return NULL;
 #endif
 	*iter = &psi_system;
 	return &psi_system;