Because percpu counters can accumulate their per-cpu sums
over time outside of the control of the callers, we need
this patch that updates the maximum values when that
happens.
I am adding a mininum value as well for conistency, due to
the signed nature of the percpu_counters.
However, I am not sure this will be of general use, and might
be yet another indication that we need to duplicate those
structures...
Signed-off-by: Glauber Costa <glommer@xxxxxxxxxxxxx>
---
include/linux/percpu_counter.h | 2 ++
include/linux/res_counter.h | 6 +-----
kernel/res_counter.c | 6 +++---
lib/percpu_counter.c | 4 ++++
4 files changed, 10 insertions(+), 8 deletions(-)
diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h
index 8310548..639d2d5 100644
--- a/include/linux/percpu_counter.h
+++ b/include/linux/percpu_counter.h
@@ -18,6 +18,8 @@
struct percpu_counter {
raw_spinlock_t lock;
s64 count;
+ s64 max;
+ s64 min;
#ifdef CONFIG_HOTPLUG_CPU
struct list_head list; /* All percpu_counters are on a list */
#endif
diff --git a/include/linux/res_counter.h b/include/linux/res_counter.h
index 8c1c20e..3527827 100644
--- a/include/linux/res_counter.h
+++ b/include/linux/res_counter.h
@@ -27,10 +27,6 @@ struct res_counter {
*/
struct percpu_counter usage_pcp;
/*
- * the maximal value of the usage from the counter creation
- */
- unsigned long long max_usage;
- /*
* the limit that usage cannot exceed
*/
unsigned long long limit;
@@ -178,7 +174,7 @@ static inline void res_counter_reset_max(struct res_counter *cnt)
unsigned long flags;
raw_spin_lock_irqsave(&cnt->usage_pcp.lock, flags);
- cnt->max_usage = __percpu_counter_sum_locked(&cnt->usage_pcp);
+ cnt->usage_pcp.max = __percpu_counter_sum_locked(&cnt->usage_pcp);
raw_spin_unlock_irqrestore(&cnt->usage_pcp.lock, flags);
}
diff --git a/kernel/res_counter.c b/kernel/res_counter.c
index 8a99943..7b05208 100644
--- a/kernel/res_counter.c
+++ b/kernel/res_counter.c
@@ -61,8 +61,8 @@ int __res_counter_add(struct res_counter *c, long val, bool fail)
c->usage_pcp.count += val;
- if (usage > c->max_usage)
- c->max_usage = usage;
+ if (usage > c->usage_pcp.max)
+ c->usage_pcp.max = usage;
out:
raw_spin_unlock(&c->usage_pcp.lock);
@@ -164,7 +164,7 @@ res_counter_member(struct res_counter *counter, int member)
{
switch (member) {
case RES_MAX_USAGE:
- return &counter->max_usage;
+ return &counter->usage_pcp.max;
case RES_LIMIT:
return &counter->limit;
case RES_FAILCNT:
diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c
index 0b6a672..6dff70b 100644
--- a/lib/percpu_counter.c
+++ b/lib/percpu_counter.c
@@ -81,6 +81,10 @@ void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch)
raw_spin_lock(&fbc->lock);
fbc->count += count;
__this_cpu_write(*fbc->counters, 0);
+ if (fbc->count > fbc->max)
+ fbc->max = fbc->count;
+ if (fbc->count < fbc->min)
+ fbc->min = fbc->count;
raw_spin_unlock(&fbc->lock);
} else {
__this_cpu_write(*fbc->counters, count);
--
1.7.4.1
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