From 102a0743326a03cd1a1202ceda21e175b7d3575c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:20:52 +0000
Subject: [PATCH] add new system file
---
kernel/lib/percpu_counter.c | 25 ++++++++++++++++++++++---
1 files changed, 22 insertions(+), 3 deletions(-)
diff --git a/kernel/lib/percpu_counter.c b/kernel/lib/percpu_counter.c
index a66595b..00f666d 100644
--- a/kernel/lib/percpu_counter.c
+++ b/kernel/lib/percpu_counter.c
@@ -17,7 +17,7 @@
#ifdef CONFIG_DEBUG_OBJECTS_PERCPU_COUNTER
-static struct debug_obj_descr percpu_counter_debug_descr;
+static const struct debug_obj_descr percpu_counter_debug_descr;
static bool percpu_counter_fixup_free(void *addr, enum debug_obj_state state)
{
@@ -33,7 +33,7 @@
}
}
-static struct debug_obj_descr percpu_counter_debug_descr = {
+static const struct debug_obj_descr percpu_counter_debug_descr = {
.name = "percpu_counter",
.fixup_free = percpu_counter_fixup_free,
};
@@ -85,7 +85,7 @@
preempt_disable();
count = __this_cpu_read(*fbc->counters) + amount;
- if (count >= batch || count <= -batch) {
+ if (abs(count) >= batch) {
unsigned long flags;
raw_spin_lock_irqsave(&fbc->lock, flags);
fbc->count += count;
@@ -99,6 +99,25 @@
EXPORT_SYMBOL(percpu_counter_add_batch);
/*
+ * For percpu_counter with a big batch, the devication of its count could
+ * be big, and there is requirement to reduce the deviation, like when the
+ * counter's batch could be runtime decreased to get a better accuracy,
+ * which can be achieved by running this sync function on each CPU.
+ */
+void percpu_counter_sync(struct percpu_counter *fbc)
+{
+ unsigned long flags;
+ s64 count;
+
+ raw_spin_lock_irqsave(&fbc->lock, flags);
+ count = __this_cpu_read(*fbc->counters);
+ fbc->count += count;
+ __this_cpu_sub(*fbc->counters, count);
+ raw_spin_unlock_irqrestore(&fbc->lock, flags);
+}
+EXPORT_SYMBOL(percpu_counter_sync);
+
+/*
* Add up all the per-cpu counts, return the result. This is a more accurate
* but much slower version of percpu_counter_read_positive()
*/
--
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