The patch titled
/proc/stat: scalability of irq num per cpu
has been added to the -mm tree. Its filename is
proc-stat-scalability-of-irq-num-per-cpu.patch
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Subject: /proc/stat: scalability of irq num per cpu
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
/proc/stat shows the total number of all interrupts to each cpu. But when
the number of IRQs are very large, it take very long time and 'cat
/proc/stat' takes more than 10 secs. This is because sum of all irq
events are counted when /proc/stat is read. This patch adds "sum of all
irq" counter percpu and reduce read costs.
The cost of reading /proc/stat is important because it's used by major
applications as 'top', 'ps', 'w', etc....
A test on a mechin (4096cpu, 256 nodes, 4592 irqs) shows
%time cat /proc/stat > /dev/null
Before Patch: 12.627 sec
After Patch: 2.459 sec
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Tested-by: Jack Steiner <steiner@xxxxxxx>
Acked-by: Jack Steiner <steiner@xxxxxxx>
Cc: Yinghai Lu <yinghai@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/stat.c | 4 +---
include/linux/kernel_stat.h | 14 ++++++++++++--
2 files changed, 13 insertions(+), 5 deletions(-)
diff -puN fs/proc/stat.c~proc-stat-scalability-of-irq-num-per-cpu fs/proc/stat.c
--- a/fs/proc/stat.c~proc-stat-scalability-of-irq-num-per-cpu
+++ a/fs/proc/stat.c
@@ -52,9 +52,7 @@ static int show_stat(struct seq_file *p,
guest = cputime64_add(guest, kstat_cpu(i).cpustat.guest);
guest_nice = cputime64_add(guest_nice,
kstat_cpu(i).cpustat.guest_nice);
- for_each_irq_nr(j) {
- sum += kstat_irqs_cpu(j, i);
- }
+ sum += kstat_cpu_irqs_sum(i);
sum += arch_irq_stat_cpu(i);
for (j = 0; j < NR_SOFTIRQS; j++) {
diff -puN include/linux/kernel_stat.h~proc-stat-scalability-of-irq-num-per-cpu include/linux/kernel_stat.h
--- a/include/linux/kernel_stat.h~proc-stat-scalability-of-irq-num-per-cpu
+++ a/include/linux/kernel_stat.h
@@ -33,6 +33,7 @@ struct kernel_stat {
#ifndef CONFIG_GENERIC_HARDIRQS
unsigned int irqs[NR_IRQS];
#endif
+ unsigned long irqs_sum;
unsigned int softirqs[NR_SOFTIRQS];
};
@@ -54,6 +55,7 @@ static inline void kstat_incr_irqs_this_
struct irq_desc *desc)
{
kstat_this_cpu.irqs[irq]++;
+ kstat_this_cpu.irqs_sum++;
}
static inline unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
@@ -65,8 +67,9 @@ static inline unsigned int kstat_irqs_cp
extern unsigned int kstat_irqs_cpu(unsigned int irq, int cpu);
#define kstat_irqs_this_cpu(DESC) \
((DESC)->kstat_irqs[smp_processor_id()])
-#define kstat_incr_irqs_this_cpu(irqno, DESC) \
- ((DESC)->kstat_irqs[smp_processor_id()]++)
+#define kstat_incr_irqs_this_cpu(irqno, DESC) do {\
+ ((DESC)->kstat_irqs[smp_processor_id()]++);\
+ kstat_this_cpu.irqs_sum++; } while (0)
#endif
@@ -94,6 +97,13 @@ static inline unsigned int kstat_irqs(un
return sum;
}
+/*
+ * Number of interrupts per cpu, since bootup
+ */
+static inline unsigned int kstat_cpu_irqs_sum(unsigned int cpu)
+{
+ return kstat_cpu(cpu).irqs_sum;
+}
/*
* Lock/unlock the current runqueue - to extract task statistics:
_
Patches currently in -mm which might be from kamezawa.hiroyu@xxxxxxxxxxxxxx are
mm-fix-return-value-of-scan_lru_pages-in-memory-unplug.patch
linux-next.patch
vfs-introduce-fmode_neg_offset-for-allowing-negative-f_pos.patch
oom-add-per-mm-oom-disable-count.patch
oom-add-per-mm-oom-disable-count-protect-oom_disable_count-with-task_lock-in-fork.patch
oom-add-per-mm-oom-disable-count-use-old_mm-for-oom_disable_count-in-exec.patch
oom-avoid-killing-a-task-if-a-thread-sharing-its-mm-cannot-be-killed.patch
oom-kill-all-threads-sharing-oom-killed-tasks-mm.patch
oom-kill-all-threads-sharing-oom-killed-tasks-mm-fix.patch
oom-kill-all-threads-sharing-oom-killed-tasks-mm-fix-fix.patch
oom-rewrite-error-handling-for-oom_adj-and-oom_score_adj-tunables.patch
oom-fix-locking-for-oom_adj-and-oom_score_adj.patch
memory-hotplug-fix-notifiers-return-value-check.patch
memory-hotplug-unify-is_removable-and-offline-detection-code.patch
memory-hotplug-unify-is_removable-and-offline-detection-code-checkpatch-fixes.patch
tracing-vmscan-add-trace-events-for-lru-list-shrinking.patch
writeback-account-for-time-spent-congestion_waited.patch
vmscan-synchronous-lumpy-reclaim-should-not-call-congestion_wait.patch
vmscan-narrow-the-scenarios-lumpy-reclaim-uses-synchrounous-reclaim.patch
vmscan-remove-dead-code-in-shrink_inactive_list.patch
vmscan-isolated_lru_pages-stop-neighbour-search-if-neighbour-cannot-be-isolated.patch
writeback-do-not-sleep-on-the-congestion-queue-if-there-are-no-congested-bdis.patch
writeback-do-not-sleep-on-the-congestion-queue-if-there-are-no-congested-bdis-or-if-significant-congestion-is-not-being-encountered-in-the-current-zone.patch
writeback-do-not-sleep-on-the-congestion-queue-if-there-are-no-congested-bdis-or-if-significant-congestion-is-not-being-encounted-in-the-current-zone-fix.patch
mm-memory_hotplugc-make-scan_lru_pages-static.patch
mm-fix-error-reporting-in-move_pages-syscall.patch
memcg-fix-race-in-file_mapped-accouting-flag-management.patch
memcg-avoid-lock-in-updating-file_mapped-was-fix-race-in-file_mapped-accouting-flag-management.patch
memcg-use-for_each_mem_cgroup.patch
memcg-cpu-hotplug-aware-percpu-count-updates.patch
memcg-cpu-hotplug-aware-percpu-count-updates-fix.patch
memcg-cpu-hotplug-aware-quick-acount_move-detection.patch
memcg-cpu-hotplug-aware-quick-acount_move-detection-checkpatch-fixes.patch
memcg-generic-filestat-update-interface.patch
proc-stat-scalability-of-irq-num-per-cpu.patch
proc-stat-fix-scalability-of-irq-sum-of-all-cpu.patch
proc-stat-fix-scalability-of-irq-sum-of-all-cpu-fix.patch
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