169 lines
6.5 KiB
Diff
169 lines
6.5 KiB
Diff
From ca2ccd52a7fd1e95801ee3a8e3cf6cd5a437473a Mon Sep 17 00:00:00 2001
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Message-Id: <ca2ccd52a7fd1e95801ee3a8e3cf6cd5a437473a.1507237258.git.Jim.Somerville@windriver.com>
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In-Reply-To: <2a9fb6a58e40e8604d97223603111e869bb774b1.1507237258.git.Jim.Somerville@windriver.com>
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References: <2a9fb6a58e40e8604d97223603111e869bb774b1.1507237258.git.Jim.Somerville@windriver.com>
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From: Chris Friesen <chris.friesen@windriver.com>
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Date: Tue, 24 Nov 2015 16:27:28 -0500
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Subject: [PATCH 05/24] affine compute kernel threads
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This is a kernel enhancement to configure the cpu affinity of kernel
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threads via kernel boot option kthread_cpus=<cpulist>. The compute
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kickstart file and compute-huge.sh scripts will update grub with the
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new option.
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With kthread_cpus specified, the cpumask is immediately applied upon
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thread launch. This does not affect kernel threads that specify cpu
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and node.
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Note: this is based off of Christoph Lameter's patch at
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https://lwn.net/Articles/565932/ with the only difference being
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the kernel parameter changed from kthread to kthread_cpus.
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Signed-off-by: Christoph Lameter <cl@linux.com>
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Signed-off-by: Chris Friesen <chris.friesen@windriver.com>
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[VT: The existing "isolcpus"
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kernel bootarg, cgroup/cpuset, and taskset might provide the some
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way to have cpu isolation. However none of them satisfies the requirements.
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Replacing spaces with tabs. Combine two calls of set_cpus_allowed_ptr()
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in kernel_init_freeable() in init/main.c into one. Performed tests]
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Signed-off-by: Vu Tran <vu.tran@windriver.com>
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Signed-off-by: Jim Somerville <Jim.Somerville@windriver.com>
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---
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Documentation/kernel-parameters.txt | 10 ++++++++++
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include/linux/cpumask.h | 2 ++
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init/main.c | 6 ++----
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kernel/cpu.c | 13 +++++++++++++
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kernel/kmod.c | 3 +++
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kernel/kthread.c | 4 ++--
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6 files changed, 32 insertions(+), 6 deletions(-)
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diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
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index cbd5f28..9c29169 100644
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--- a/Documentation/kernel-parameters.txt
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+++ b/Documentation/kernel-parameters.txt
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@@ -1482,6 +1482,16 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
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kstack=N [X86] Print N words from the kernel stack
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in oops dumps.
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+ kthread_cpus= [KNL, SMP] Only run kernel threads on the specified
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+ list of processors. The kernel will start threads
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+ on the indicated processors only (unless there
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+ are specific reasons to run a thread with
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+ different affinities). This can be used to make
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+ init start on certain processors and also to
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+ control where kmod and other user space threads
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+ are being spawned. Allows to keep kernel threads
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+ away from certain cores unless absoluteluy necessary.
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+
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kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
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Default is 0 (don't ignore, but inject #GP)
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diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
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index ca6c077..1f1420d 100644
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--- a/include/linux/cpumask.h
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+++ b/include/linux/cpumask.h
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@@ -52,6 +52,7 @@ extern int nr_cpu_ids;
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* cpu_present_mask - has bit 'cpu' set iff cpu is populated
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* cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler
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* cpu_active_mask - has bit 'cpu' set iff cpu available to migration
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+ * cpu_kthread_mask - has bit 'cpu' set iff general kernel threads allowed
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*
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* If !CONFIG_HOTPLUG_CPU, present == possible, and active == online.
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*
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@@ -88,6 +89,7 @@ extern const struct cpumask *const cpu_possible_mask;
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extern const struct cpumask *const cpu_online_mask;
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extern const struct cpumask *const cpu_present_mask;
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extern const struct cpumask *const cpu_active_mask;
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+extern const struct cpumask *const cpu_kthread_mask;
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#if NR_CPUS > 1
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#define num_online_cpus() cpumask_weight(cpu_online_mask)
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diff --git a/init/main.c b/init/main.c
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index d7bc443..3efc7dd 100644
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--- a/init/main.c
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+++ b/init/main.c
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@@ -943,10 +943,6 @@ static noinline void __init kernel_init_freeable(void)
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* init can allocate pages on any node
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*/
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set_mems_allowed(node_states[N_MEMORY]);
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- /*
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- * init can run on any cpu.
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- */
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- set_cpus_allowed_ptr(current, cpu_all_mask);
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cad_pid = task_pid(current);
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@@ -962,6 +958,8 @@ static noinline void __init kernel_init_freeable(void)
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do_basic_setup();
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+ set_cpus_allowed_ptr(current, cpu_kthread_mask);
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+
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/* Open the /dev/console on the rootfs, this should never fail */
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if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
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pr_err("Warning: unable to open an initial console.\n");
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diff --git a/kernel/cpu.c b/kernel/cpu.c
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index 6442ecf..c610377 100644
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--- a/kernel/cpu.c
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+++ b/kernel/cpu.c
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@@ -713,6 +713,19 @@ static DECLARE_BITMAP(cpu_active_bits, CONFIG_NR_CPUS) __read_mostly;
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const struct cpumask *const cpu_active_mask = to_cpumask(cpu_active_bits);
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EXPORT_SYMBOL(cpu_active_mask);
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+static DECLARE_BITMAP(cpu_kthread_bits, CONFIG_NR_CPUS) __read_mostly
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+ = CPU_BITS_ALL;
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+const struct cpumask *const cpu_kthread_mask = to_cpumask(cpu_kthread_bits);
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+EXPORT_SYMBOL(cpu_kthread_mask);
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+
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+static int __init kthread_setup(char *str)
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+{
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+ cpulist_parse(str, (struct cpumask *)&cpu_kthread_bits);
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+ return 1;
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+}
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+__setup("kthread_cpus=", kthread_setup);
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+
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+
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void set_cpu_possible(unsigned int cpu, bool possible)
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{
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if (possible)
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diff --git a/kernel/kmod.c b/kernel/kmod.c
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index 86ab754..4bf584b 100644
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--- a/kernel/kmod.c
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+++ b/kernel/kmod.c
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@@ -204,6 +204,9 @@ static int ____call_usermodehelper(void *data)
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flush_signal_handlers(current, 1);
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spin_unlock_irq(¤t->sighand->siglock);
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+ /* We can run only where init is allowed to run. */
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+ set_cpus_allowed_ptr(current, cpu_kthread_mask);
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+
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/*
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* Our parent is keventd, which runs with elevated scheduling priority.
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* Avoid propagating that into the userspace child.
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diff --git a/kernel/kthread.c b/kernel/kthread.c
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index 703d910..7ea32eb 100644
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--- a/kernel/kthread.c
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+++ b/kernel/kthread.c
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@@ -284,7 +284,7 @@ struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
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* The kernel thread should not inherit these properties.
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*/
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sched_setscheduler_nocheck(create.result, SCHED_NORMAL, ¶m);
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- set_cpus_allowed_ptr(create.result, cpu_all_mask);
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+ set_cpus_allowed_ptr(create.result, cpu_kthread_mask);
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}
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return create.result;
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}
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@@ -454,7 +454,7 @@ int kthreadd(void *unused)
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/* Setup a clean context for our children to inherit. */
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set_task_comm(tsk, "kthreadd");
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ignore_signals(tsk);
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- set_cpus_allowed_ptr(tsk, cpu_all_mask);
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+ set_cpus_allowed_ptr(tsk, cpu_kthread_mask);
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set_mems_allowed(node_states[N_MEMORY]);
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current->flags |= PF_NOFREEZE;
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--
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1.8.3.1
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