From: Barry Song <[email protected]>
When unplugging a CPU, the current code merges its vm_events
with an online CPU. Because, during summation, it only considers
online CPUs, which is a crude workaround. By transitioning to
summing up all possible CPUs, we can eliminate the need for
vm_events_fold_cpu.
Suggested-by: Ryan Roberts <[email protected]>
Signed-off-by: Barry Song <[email protected]>
---
-v1:
originally suggested by Ryan while he reviewed mTHP counters
patchset[1]; I am also applying this suggestion to vm_events
[1] https://lore.kernel.org/linux-mm/[email protected]/
include/linux/vmstat.h | 5 -----
mm/page_alloc.c | 8 --------
mm/vmstat.c | 19 +------------------
3 files changed, 1 insertion(+), 31 deletions(-)
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 735eae6e272c..f7eaeb8bfa47 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -83,8 +83,6 @@ static inline void count_vm_events(enum vm_event_item item, long delta)
extern void all_vm_events(unsigned long *);
-extern void vm_events_fold_cpu(int cpu);
-
#else
/* Disable counters */
@@ -103,9 +101,6 @@ static inline void __count_vm_events(enum vm_event_item item, long delta)
static inline void all_vm_events(unsigned long *ret)
{
}
-static inline void vm_events_fold_cpu(int cpu)
-{
-}
#endif /* CONFIG_VM_EVENT_COUNTERS */
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b51becf03d1e..640d5752e400 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5832,14 +5832,6 @@ static int page_alloc_cpu_dead(unsigned int cpu)
mlock_drain_remote(cpu);
drain_pages(cpu);
- /*
- * Spill the event counters of the dead processor
- * into the current processors event counters.
- * This artificially elevates the count of the current
- * processor.
- */
- vm_events_fold_cpu(cpu);
-
/*
* Zero the differential counters of the dead processor
* so that the vm statistics are consistent.
diff --git a/mm/vmstat.c b/mm/vmstat.c
index db79935e4a54..bae6ff476870 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -114,7 +114,7 @@ static void sum_vm_events(unsigned long *ret)
memset(ret, 0, NR_VM_EVENT_ITEMS * sizeof(unsigned long));
- for_each_online_cpu(cpu) {
+ for_each_possible_cpu(cpu) {
struct vm_event_state *this = &per_cpu(vm_event_states, cpu);
for (i = 0; i < NR_VM_EVENT_ITEMS; i++)
@@ -135,23 +135,6 @@ void all_vm_events(unsigned long *ret)
}
EXPORT_SYMBOL_GPL(all_vm_events);
-/*
- * Fold the foreign cpu events into our own.
- *
- * This is adding to the events on one processor
- * but keeps the global counts constant.
- */
-void vm_events_fold_cpu(int cpu)
-{
- struct vm_event_state *fold_state = &per_cpu(vm_event_states, cpu);
- int i;
-
- for (i = 0; i < NR_VM_EVENT_ITEMS; i++) {
- count_vm_events(i, fold_state->event[i]);
- fold_state->event[i] = 0;
- }
-}
-
#endif /* CONFIG_VM_EVENT_COUNTERS */
/*
--
2.34.1