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From:   Li RongQing <lirongqing@baidu.com>
To:     peterz@infradead.org, frederic@kernel.org, tglx@linutronix.de,
        mingo@kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH][RFC] sched/isolation: allow isolcpus and nohz_full for different cpus
Date:   Thu,  9 Apr 2020 15:57:56 +0800
Message-Id: <1586419076-6301-1-git-send-email-lirongqing@baidu.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

when both isolcpus and nohz_full are set, their cpus must be
same now, in fact isolcpus and nohz_full are not related, and
different cpus are expected for some cases, for example, some
cores for polling threads wants to isolcpus, and some cores for
dedicated threads, only nohz_full is expected

Signed-off-by: Li RongQing <lirongqing@baidu.com>
---
 kernel/sched/isolation.c | 79 ++++++++++++++++++++++++++++++++----------------
 1 file changed, 53 insertions(+), 26 deletions(-)

diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 008d6ac2342b..6e6be34bb796 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -11,7 +11,8 @@
 
 DEFINE_STATIC_KEY_FALSE(housekeeping_overridden);
 EXPORT_SYMBOL_GPL(housekeeping_overridden);
-static cpumask_var_t housekeeping_mask;
+static cpumask_var_t housekeeping_mask_isolcpus;
+static cpumask_var_t housekeeping_mask_nohz_full;
 static unsigned int housekeeping_flags;
 
 bool housekeeping_enabled(enum hk_flags flags)
@@ -20,12 +21,26 @@ bool housekeeping_enabled(enum hk_flags flags)
 }
 EXPORT_SYMBOL_GPL(housekeeping_enabled);
 
+static cpumask_var_t housekeeping_get_mask(enum hk_flags flags)
+{
+	if (flags & (HK_FLAG_DOMAIN | HK_FLAG_MANAGED_IRQ))
+		return housekeeping_mask_isolcpus;
+
+	/* set by isolcpus=nohz only */
+	if ((flags & HK_FLAG_TICK) && !(housekeeping_flags & HK_FLAG_RCU))
+		return housekeeping_mask_isolcpus;
+
+	return housekeeping_mask_nohz_full;
+}
+
 int housekeeping_any_cpu(enum hk_flags flags)
 {
+	cpumask_var_t housekeeping_mask;
 	int cpu;
 
 	if (static_branch_unlikely(&housekeeping_overridden)) {
 		if (housekeeping_flags & flags) {
+			housekeeping_mask = housekeeping_get_mask(flags);
 			cpu = sched_numa_find_closest(housekeeping_mask, smp_processor_id());
 			if (cpu < nr_cpu_ids)
 				return cpu;
@@ -41,7 +56,7 @@ const struct cpumask *housekeeping_cpumask(enum hk_flags flags)
 {
 	if (static_branch_unlikely(&housekeeping_overridden))
 		if (housekeeping_flags & flags)
-			return housekeeping_mask;
+			return housekeeping_get_mask(flags);
 	return cpu_possible_mask;
 }
 EXPORT_SYMBOL_GPL(housekeeping_cpumask);
@@ -49,16 +64,24 @@ EXPORT_SYMBOL_GPL(housekeeping_cpumask);
 void housekeeping_affine(struct task_struct *t, enum hk_flags flags)
 {
 	if (static_branch_unlikely(&housekeeping_overridden))
-		if (housekeeping_flags & flags)
+		if (housekeeping_flags & flags) {
+			cpumask_var_t housekeeping_mask;
+
+			housekeeping_mask = housekeeping_get_mask(flags);
 			set_cpus_allowed_ptr(t, housekeeping_mask);
+		}
 }
 EXPORT_SYMBOL_GPL(housekeeping_affine);
 
 bool housekeeping_test_cpu(int cpu, enum hk_flags flags)
 {
 	if (static_branch_unlikely(&housekeeping_overridden))
-		if (housekeeping_flags & flags)
+		if (housekeeping_flags & flags) {
+			cpumask_var_t housekeeping_mask;
+
+			housekeeping_mask = housekeeping_get_mask(flags);
 			return cpumask_test_cpu(cpu, housekeeping_mask);
+		}
 	return true;
 }
 EXPORT_SYMBOL_GPL(housekeeping_test_cpu);
@@ -74,10 +97,14 @@ void __init housekeeping_init(void)
 		sched_tick_offload_init();
 
 	/* We need at least one CPU to handle housekeeping work */
-	WARN_ON_ONCE(cpumask_empty(housekeeping_mask));
+	if (housekeeping_mask_isolcpus)
+		WARN_ON_ONCE(cpumask_empty(housekeeping_mask_isolcpus));
+	if (housekeeping_mask_nohz_full)
+		WARN_ON_ONCE(cpumask_empty(housekeeping_mask_nohz_full));
 }
 
-static int __init housekeeping_setup(char *str, enum hk_flags flags)
+static int __init housekeeping_setup(char *str, enum hk_flags flags,
+		cpumask_var_t *housekeeping_mask)
 {
 	cpumask_var_t non_housekeeping_mask;
 	cpumask_var_t tmp;
@@ -92,25 +119,25 @@ static int __init housekeeping_setup(char *str, enum hk_flags flags)
 	}
 
 	alloc_bootmem_cpumask_var(&tmp);
-	if (!housekeeping_flags) {
-		alloc_bootmem_cpumask_var(&housekeeping_mask);
-		cpumask_andnot(housekeeping_mask,
-			       cpu_possible_mask, non_housekeeping_mask);
-
-		cpumask_andnot(tmp, cpu_present_mask, non_housekeeping_mask);
-		if (cpumask_empty(tmp)) {
-			pr_warn("Housekeeping: must include one present CPU, "
+	alloc_bootmem_cpumask_var(housekeeping_mask);
+	cpumask_andnot(*housekeeping_mask,
+				   cpu_possible_mask, non_housekeeping_mask);
+
+	cpumask_andnot(tmp, cpu_present_mask, non_housekeeping_mask);
+	if (cpumask_empty(tmp)) {
+		pr_warn("Housekeeping: must include one present CPU, "
 				"using boot CPU:%d\n", smp_processor_id());
-			__cpumask_set_cpu(smp_processor_id(), housekeeping_mask);
-			__cpumask_clear_cpu(smp_processor_id(), non_housekeeping_mask);
-		}
-	} else {
-		cpumask_andnot(tmp, cpu_present_mask, non_housekeeping_mask);
-		if (cpumask_empty(tmp))
-			__cpumask_clear_cpu(smp_processor_id(), non_housekeeping_mask);
-		cpumask_andnot(tmp, cpu_possible_mask, non_housekeeping_mask);
-		if (!cpumask_equal(tmp, housekeeping_mask)) {
-			pr_warn("Housekeeping: nohz_full= must match isolcpus=\n");
+		__cpumask_set_cpu(smp_processor_id(), *housekeeping_mask);
+		__cpumask_clear_cpu(smp_processor_id(), non_housekeeping_mask);
+	}
+
+	/* cpus should match when both nohz_full and isolcpus
+	 * with nohz are passed into kernel
+	 */
+	if (housekeeping_flags & flags & HK_FLAG_TICK) {
+		if (!cpumask_equal(housekeeping_mask_nohz_full,
+					housekeeping_mask_isolcpus)) {
+			pr_warn("Housekeeping: nohz_full= must match isolcpus=nohz\n");
 			free_bootmem_cpumask_var(tmp);
 			free_bootmem_cpumask_var(non_housekeeping_mask);
 			return 0;
@@ -142,7 +169,7 @@ static int __init housekeeping_nohz_full_setup(char *str)
 
 	flags = HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | HK_FLAG_RCU | HK_FLAG_MISC;
 
-	return housekeeping_setup(str, flags);
+	return housekeeping_setup(str, flags, &housekeeping_mask_nohz_full);
 }
 __setup("nohz_full=", housekeeping_nohz_full_setup);
 
@@ -177,6 +204,6 @@ static int __init housekeeping_isolcpus_setup(char *str)
 	if (!flags)
 		flags |= HK_FLAG_DOMAIN;
 
-	return housekeeping_setup(str, flags);
+	return housekeeping_setup(str, flags, &housekeeping_mask_isolcpus);
 }
 __setup("isolcpus=", housekeeping_isolcpus_setup);
-- 
2.16.2