From: Chris Metcalf <cmetcalf@ezchip.com>
To: Gilad Ben Yossef <giladb@ezchip.com>, Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@kernel.org>, Peter Zijlstra <peterz@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        "Rik van Riel" <riel@redhat.com>, Tejun Heo <tj@kernel.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Christoph Lameter <cl@linux.com>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Andy Lutomirski <luto@amacapital.net>, <linux-doc@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
CC: Chris Metcalf <cmetcalf@ezchip.com>
Subject: [PATCH v10 05/12] task_isolation: support CONFIG_TASK_ISOLATION_ALL
Date: Wed, 2 Mar 2016 15:09:29 -0500
Message-ID: <1456949376-4910-6-git-send-email-cmetcalf@ezchip.com>
In-Reply-To: <1456949376-4910-1-git-send-email-cmetcalf@ezchip.com>
References: <1456949376-4910-1-git-send-email-cmetcalf@ezchip.com>
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This option, similar to NO_HZ_FULL_ALL, simplifies configuring
a system to boot by default with all cores except the boot core
running in task isolation mode.
---
 init/Kconfig       | 10 ++++++++++
 kernel/isolation.c |  6 ++++++
 2 files changed, 16 insertions(+)

diff --git a/init/Kconfig b/init/Kconfig
index 6cab348fe454..314b09347fba 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -802,6 +802,16 @@ config TASK_ISOLATION
 	 You should say "N" unless you are intending to run a
 	 high-performance userspace driver or similar task.
 
+config TASK_ISOLATION_ALL
+	bool "Provide task isolation on all CPUs by default (except CPU 0)"
+	depends on TASK_ISOLATION
+	help
+	 If the user doesn't pass the task_isolation boot option to
+	 define the range of task isolation CPUs, consider that all
+	 CPUs in the system are task isolation by default.
+	 Note the boot CPU will still be kept outside the range to
+	 handle timekeeping duty, etc.
+
 config BUILD_BIN2C
 	bool
 	default n
diff --git a/kernel/isolation.c b/kernel/isolation.c
index e954afd8cce8..42ad7a746a1e 100644
--- a/kernel/isolation.c
+++ b/kernel/isolation.c
@@ -40,8 +40,14 @@ int __init task_isolation_init(void)
 {
 	/* For offstack cpumask, ensure we allocate an empty cpumask early. */
 	if (!saw_boot_arg) {
+#ifdef CONFIG_TASK_ISOLATION_ALL
+		alloc_cpumask_var(&task_isolation_map, GFP_KERNEL);
+		cpumask_copy(task_isolation_map, cpu_possible_mask);
+		cpumask_clear_cpu(smp_processor_id(), task_isolation_map);
+#else
 		zalloc_cpumask_var(&task_isolation_map, GFP_KERNEL);
 		return 0;
+#endif
 	}
 
 	/*
-- 
2.1.2