[kernel/f16] Add patch to fix cpu pinning after suspend/resume (rhbz 714271)
Josh Boyer
jwboyer at fedoraproject.org
Wed Jul 25 12:07:17 UTC 2012
commit 0e04e7c4764f828f62c0b6d61f1b0cb7e862e0a7
Author: Josh Boyer <jwboyer at redhat.com>
Date: Tue Jul 24 12:59:03 2012 -0400
Add patch to fix cpu pinning after suspend/resume (rhbz 714271)
...pusets-suspend-Dont-modify-cpusets-during.patch | 139 ++++++++++++++++++++
kernel.spec | 11 ++-
2 files changed, 149 insertions(+), 1 deletions(-)
---
diff --git a/CPU-hotplug-cpusets-suspend-Dont-modify-cpusets-during.patch b/CPU-hotplug-cpusets-suspend-Dont-modify-cpusets-during.patch
new file mode 100644
index 0000000..f57ecee
--- /dev/null
+++ b/CPU-hotplug-cpusets-suspend-Dont-modify-cpusets-during.patch
@@ -0,0 +1,139 @@
+From 0c1508129adc051fabaf8debefea79baa2f1a81b Mon Sep 17 00:00:00 2001
+From: "Srivatsa S. Bhat" <srivatsa.bhat at linux.vnet.ibm.com>
+Date: Thu, 24 May 2012 19:46:26 +0530
+Subject: [PATCH] CPU hotplug, cpusets, suspend: Don't modify cpusets during
+ suspend/resume
+
+In the event of CPU hotplug, the kernel modifies the cpusets' cpus_allowed
+masks as and when necessary to ensure that the tasks belonging to the cpusets
+have some place (online CPUs) to run on. And regular CPU hotplug is
+destructive in the sense that the kernel doesn't remember the original cpuset
+configurations set by the user, across hotplug operations.
+
+However, suspend/resume (which uses CPU hotplug) is a special case in which
+the kernel has the responsibility to restore the system (during resume), to
+exactly the same state it was in before suspend.
+
+In order to achieve that, do the following:
+
+1. Don't modify cpusets during suspend/resume. At all.
+ In particular, don't move the tasks from one cpuset to another, and
+ don't modify any cpuset's cpus_allowed mask. So, simply ignore cpusets
+ during the CPU hotplug operations that are carried out in the
+ suspend/resume path.
+
+2. However, cpusets and sched domains are related. We just want to avoid
+ altering cpusets alone. So, to keep the sched domains updated, build
+ a single sched domain (containing all active cpus) during each of the
+ CPU hotplug operations carried out in s/r path, effectively ignoring
+ the cpusets' cpus_allowed masks.
+
+ (Since userspace is frozen while doing all this, it will go unnoticed.)
+
+3. During the last CPU online operation during resume, build the sched
+ domains by looking up the (unaltered) cpusets' cpus_allowed masks.
+ That will bring back the system to the same original state as it was in
+ before suspend.
+
+Ultimately, this will not only solve the cpuset problem related to suspend
+resume (ie., restores the cpusets to exactly what it was before suspend, by
+not touching it at all) but also speeds up suspend/resume because we avoid
+running cpuset update code for every CPU being offlined/onlined.
+
+Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat at linux.vnet.ibm.com>
+Signed-off-by: Peter Zijlstra <a.p.zijlstra at chello.nl>
+Cc: Linus Torvalds <torvalds at linux-foundation.org>
+Cc: Andrew Morton <akpm at linux-foundation.org>
+Cc: Thomas Gleixner <tglx at linutronix.de>
+Link: http://lkml.kernel.org/r/20120524141611.3692.20155.stgit@srivatsabhat.in.ibm.com
+Signed-off-by: Ingo Molnar <mingo at kernel.org>
+---
+ kernel/cpuset.c | 3 +++
+ kernel/sched/core.c | 40 ++++++++++++++++++++++++++++++++++++----
+ 2 files changed, 39 insertions(+), 4 deletions(-)
+
+--- linux-3.4.6-3.1.fc17.noarch.orig/kernel/cpuset.c
++++ linux-3.4.6-3.1.fc17.noarch/kernel/cpuset.c
+@@ -2065,6 +2065,9 @@ static void scan_for_empty_cpusets(struc
+ * (of no affect) on systems that are actively using CPU hotplug
+ * but making no active use of cpusets.
+ *
++ * The only exception to this is suspend/resume, where we don't
++ * modify cpusets at all.
++ *
+ * This routine ensures that top_cpuset.cpus_allowed tracks
+ * cpu_active_mask on each CPU hotplug (cpuhp) event.
+ *
+--- linux-3.4.6-3.1.fc17.noarch.orig/kernel/sched/core.c
++++ linux-3.4.6-3.1.fc17.noarch/kernel/sched/core.c
+@@ -6931,34 +6931,66 @@ int __init sched_create_sysfs_power_savi
+ }
+ #endif /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
+
++static int num_cpus_frozen; /* used to mark begin/end of suspend/resume */
++
+ /*
+ * Update cpusets according to cpu_active mask. If cpusets are
+ * disabled, cpuset_update_active_cpus() becomes a simple wrapper
+ * around partition_sched_domains().
++ *
++ * If we come here as part of a suspend/resume, don't touch cpusets because we
++ * want to restore it back to its original state upon resume anyway.
+ */
+ static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
+ void *hcpu)
+ {
+- switch (action & ~CPU_TASKS_FROZEN) {
++ switch (action) {
++ case CPU_ONLINE_FROZEN:
++ case CPU_DOWN_FAILED_FROZEN:
++
++ /*
++ * num_cpus_frozen tracks how many CPUs are involved in suspend
++ * resume sequence. As long as this is not the last online
++ * operation in the resume sequence, just build a single sched
++ * domain, ignoring cpusets.
++ */
++ num_cpus_frozen--;
++ if (likely(num_cpus_frozen)) {
++ partition_sched_domains(1, NULL, NULL);
++ break;
++ }
++
++ /*
++ * This is the last CPU online operation. So fall through and
++ * restore the original sched domains by considering the
++ * cpuset configurations.
++ */
++
+ case CPU_ONLINE:
+ case CPU_DOWN_FAILED:
+ cpuset_update_active_cpus();
+- return NOTIFY_OK;
++ break;
+ default:
+ return NOTIFY_DONE;
+ }
++ return NOTIFY_OK;
+ }
+
+ static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action,
+ void *hcpu)
+ {
+- switch (action & ~CPU_TASKS_FROZEN) {
++ switch (action) {
+ case CPU_DOWN_PREPARE:
+ cpuset_update_active_cpus();
+- return NOTIFY_OK;
++ break;
++ case CPU_DOWN_PREPARE_FROZEN:
++ num_cpus_frozen++;
++ partition_sched_domains(1, NULL, NULL);
++ break;
+ default:
+ return NOTIFY_DONE;
+ }
++ return NOTIFY_OK;
+ }
+
+ void __init sched_init_smp(void)
diff --git a/kernel.spec b/kernel.spec
index 420764e..2069a06 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -54,7 +54,7 @@ Summary: The Linux kernel
# For non-released -rc kernels, this will be appended after the rcX and
# gitX tags, so a 3 here would become part of release "0.rcX.gitX.3"
#
-%global baserelease 1
+%global baserelease 2
%global fedora_build %{baserelease}
# base_sublevel is the kernel version we're starting with and patching
@@ -761,6 +761,9 @@ Patch22056: crypto-aesni-intel-fix-wrong-kfree-pointer.patch
#rhbz 772730
Patch22058: ACPI-AC-check-the-return-value-of-power_supply_register.patch
+#rhbz 714271
+Patch22060: CPU-hotplug-cpusets-suspend-Dont-modify-cpusets-during.patch
+
# END OF PATCH DEFINITIONS
%endif
@@ -1409,6 +1412,9 @@ ApplyPatch crypto-aesni-intel-fix-wrong-kfree-pointer.patch
#rhbz 772730
ApplyPatch ACPI-AC-check-the-return-value-of-power_supply_register.patch
+#rhbz 714271
+ApplyPatch CPU-hotplug-cpusets-suspend-Dont-modify-cpusets-during.patch
+
# END OF PATCH APPLICATIONS
%endif
@@ -2147,6 +2153,9 @@ fi
# and build.
%changelog
+* Wed Jul 25 2012 Josh Boyer <jwboyer at redhat.com>
+- Add patch to fix cpu pinning after suspend/resume (rhbz 714271)
+
* Thu Jul 19 2012 Josh Boyer <jwboyer at redhat.com> - 3.4.6-1
- Linux v3.4.6
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