The patch titled
percpu_counters(): use cpu notifiers
has been removed from the -mm tree. Its filename was
percpu_counters-use-cpu-notifiers.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
Subject: percpu_counters(): use cpu notifiers
From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
per-cpu counters presently must iterate over all possible CPUs in the
exhaustive percpu_counter_sum().
But it can be much better to only iterate over the presently-online CPUs. To
do this, we must arrange for an offlined CPU's count to be spilled into the
counter's central count.
We can do this for all percpu_counters in the machine by linking them into a
single global list and walking that list at CPU_DEAD time.
(I hope. Might have race windows in which the percpu_counter_sum() count is
inaccurate?)
Cc: Gautham R Shenoy <ego@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/percpu_counter.h | 18 ++------
lib/percpu_counter.c | 66 +++++++++++++++++++++++++++++++
2 files changed, 72 insertions(+), 12 deletions(-)
diff -puN include/linux/percpu_counter.h~percpu_counters-use-cpu-notifiers include/linux/percpu_counter.h
--- a/include/linux/percpu_counter.h~percpu_counters-use-cpu-notifiers
+++ a/include/linux/percpu_counter.h
@@ -8,6 +8,7 @@
#include <linux/spinlock.h>
#include <linux/smp.h>
+#include <linux/list.h>
#include <linux/threads.h>
#include <linux/percpu.h>
#include <linux/types.h>
@@ -17,6 +18,9 @@
struct percpu_counter {
spinlock_t lock;
s64 count;
+#ifdef CONFIG_HOTPLUG_CPU
+ struct list_head list; /* All percpu_counters are on a list */
+#endif
s32 *counters;
};
@@ -26,18 +30,8 @@ struct percpu_counter {
#define FBC_BATCH (NR_CPUS*4)
#endif
-static inline void percpu_counter_init(struct percpu_counter *fbc, s64 amount)
-{
- spin_lock_init(&fbc->lock);
- fbc->count = amount;
- fbc->counters = alloc_percpu(s32);
-}
-
-static inline void percpu_counter_destroy(struct percpu_counter *fbc)
-{
- free_percpu(fbc->counters);
-}
-
+void percpu_counter_init(struct percpu_counter *fbc, s64 amount);
+void percpu_counter_destroy(struct percpu_counter *fbc);
void percpu_counter_mod(struct percpu_counter *fbc, s32 amount);
s64 percpu_counter_sum(struct percpu_counter *fbc);
diff -puN lib/percpu_counter.c~percpu_counters-use-cpu-notifiers lib/percpu_counter.c
--- a/lib/percpu_counter.c~percpu_counters-use-cpu-notifiers
+++ a/lib/percpu_counter.c
@@ -3,8 +3,17 @@
*/
#include <linux/percpu_counter.h>
+#include <linux/notifier.h>
+#include <linux/mutex.h>
+#include <linux/init.h>
+#include <linux/cpu.h>
#include <linux/module.h>
+#ifdef CONFIG_HOTPLUG_CPU
+static LIST_HEAD(percpu_counters);
+static DEFINE_MUTEX(percpu_counters_lock);
+#endif
+
void percpu_counter_mod(struct percpu_counter *fbc, s32 amount)
{
long count;
@@ -44,3 +53,60 @@ s64 percpu_counter_sum(struct percpu_cou
return ret < 0 ? 0 : ret;
}
EXPORT_SYMBOL(percpu_counter_sum);
+
+void percpu_counter_init(struct percpu_counter *fbc, s64 amount)
+{
+ spin_lock_init(&fbc->lock);
+ fbc->count = amount;
+ fbc->counters = alloc_percpu(s32);
+#ifdef CONFIG_HOTPLUG_CPU
+ mutex_lock(&percpu_counters_lock);
+ list_add(&fbc->list, &percpu_counters);
+ mutex_unlock(&percpu_counters_lock);
+#endif
+}
+EXPORT_SYMBOL(percpu_counter_init);
+
+void percpu_counter_destroy(struct percpu_counter *fbc)
+{
+ free_percpu(fbc->counters);
+#ifdef CONFIG_HOTPLUG_CPU
+ mutex_lock(&percpu_counters_lock);
+ list_del(&fbc->list);
+ mutex_unlock(&percpu_counters_lock);
+#endif
+}
+EXPORT_SYMBOL(percpu_counter_destroy);
+
+#ifdef CONFIG_HOTPLUG_CPU
+static int __cpuinit percpu_counter_hotcpu_callback(struct notifier_block *nb,
+ unsigned long action, void *hcpu)
+{
+ unsigned int cpu;
+ struct percpu_counter *fbc;
+
+ if (action != CPU_DEAD)
+ return NOTIFY_OK;
+
+ cpu = (unsigned long)hcpu;
+ mutex_lock(&percpu_counters_lock);
+ list_for_each_entry(fbc, &percpu_counters, list) {
+ s32 *pcount;
+
+ spin_lock(&fbc->lock);
+ pcount = per_cpu_ptr(fbc->counters, cpu);
+ fbc->count += *pcount;
+ *pcount = 0;
+ spin_unlock(&fbc->lock);
+ }
+ mutex_unlock(&percpu_counters_lock);
+ return NOTIFY_OK;
+}
+
+static int __init percpu_counter_startup(void)
+{
+ hotcpu_notifier(percpu_counter_hotcpu_callback, 0);
+ return 0;
+}
+module_init(percpu_counter_startup);
+#endif
_
Patches currently in -mm which might be from akpm@xxxxxxxxxxxxxxxxxxxx are
origin.patch
sysctlc-add-text-telling-people-to-use-ctl_unnumbered-fix.patch
git-acpi.patch
git-acpi-fix-git-rejects.patch
git-alsa.patch
working-3d-dri-intel-agpko-resume-for-i815-chip.patch
git-cifs.patch
git-powerpc.patch
revert-gregkh-driver-block-device.patch
driver-core-check-return-code-of-sysfs_create_link.patch
revert-saa7134-fix-thread-shutdown-handling.patch
git-dvb.patch
git-dvb-saa7134-tvaudio-fix.patch
git-ia64.patch
git-kbuild.patch
git-kbuild-fixup.patch
git-kvm.patch
git-leds.patch
libata-add-irq_flags-to-struct-pata_platform_info-fix.patch
git-mips-fixup.patch
git-mtd.patch
git-ubi.patch
e1000new-build-fix.patch
e1000new-build-fix-2.patch
git-ocfs2-fixup.patch
revert-gregkh-pci-pci_bridge-device.patch
aacraid-rename-check_reset.patch
git-unionfs.patch
git-block-vs-git-unionfs.patch
git-watchdog.patch
x86_64-mm-xen-attempt-to-patch-inline-versions-of-common-operations.patch
fix-x86_64-numa-fake-apicid_to_node-mapping-for-fake-numa-2.patch
fix-x86_64-mm-sched-clock-share.patch
fix-x86_64-mm-add-common-orderly_poweroff.patch
i386-add-support-for-picopower-irq-router.patch
x86_64-extract-helper-function-from-e820_register_active_regions.patch
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x86_64-fix-smp_call_function_single-return-value.patch
i386-flush_tlb_kernel_range-add-reference-to-the-arguments.patch
mmconfig-validate-against-acpi-motherboard-resources.patch
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paravirt-helper-to-disable-all-io-space-fix.patch
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x86_64-get-mp_bus_to_node-as-early.patch
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ich-force-hpet-ich5-quirk-to-force-detect-enable.patch
git-xfs.patch
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maps2-move-the-page-walker-code-to-lib.patch
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mm-clean-up-and-kernelify-shrinker-registration-vs-git-nfs.patch
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writeback-fix-time-ordering-of-the-per-superblock-dirty-inode-lists-3.patch
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