Re: [patch] sched: skip updating rq's next_balance under null SD
* Siddha, Suresh B <[EMAIL PROTECTED]> wrote: > Was playing with sched_smt_power_savings/sched_mc_power_savings and > found out that while the scheduler domains are reconstructed when > sysfs settings change, rebalance_domains() can get triggered with null > domain on other cpus, which is setting next_balance to jiffies + > 60*HZ. Resulting in no idle/busy balancing for 60 seconds. > > Fix this. thanks, applied. Ingo - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [patch] sched: skip updating rq's next_balance under null SD
* Siddha, Suresh B [EMAIL PROTECTED] wrote: Was playing with sched_smt_power_savings/sched_mc_power_savings and found out that while the scheduler domains are reconstructed when sysfs settings change, rebalance_domains() can get triggered with null domain on other cpus, which is setting next_balance to jiffies + 60*HZ. Resulting in no idle/busy balancing for 60 seconds. Fix this. thanks, applied. Ingo - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[patch] sched: skip updating rq's next_balance under null SD
Was playing with sched_smt_power_savings/sched_mc_power_savings and found
out that while the scheduler domains are reconstructed when sysfs settings
change, rebalance_domains() can get triggered with null domain on other cpus,
which is setting next_balance to jiffies + 60*HZ. Resulting in no idle/busy
balancing for 60 seconds.
Fix this.
Signed-off-by: Suresh Siddha <[EMAIL PROTECTED]>
---
diff --git a/kernel/sched.c b/kernel/sched.c
index 45e17b8..74565c0 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3020,6 +3020,7 @@ static inline void rebalance_domains(int cpu, enum
cpu_idle_type idle)
struct sched_domain *sd;
/* Earliest time when we have to do rebalance again */
unsigned long next_balance = jiffies + 60*HZ;
+ int update_next_balance = 0;
for_each_domain(cpu, sd) {
if (!(sd->flags & SD_LOAD_BALANCE))
@@ -3056,8 +3057,10 @@ static inline void rebalance_domains(int cpu, enum
cpu_idle_type idle)
if (sd->flags & SD_SERIALIZE)
spin_unlock();
out:
- if (time_after(next_balance, sd->last_balance + interval))
+ if (time_after(next_balance, sd->last_balance + interval)) {
next_balance = sd->last_balance + interval;
+ update_next_balance = 1;
+ }
/*
* Stop the load balance at this level. There is another
@@ -3067,7 +3070,14 @@ out:
if (!balance)
break;
}
- rq->next_balance = next_balance;
+
+ /*
+* next_balance will be updated only when there is a need.
+* When the cpu is attached to null domain for ex, it will not be
+* updated.
+*/
+ if (likely(update_next_balance))
+ rq->next_balance = next_balance;
}
/*
-
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[patch] sched: skip updating rq's next_balance under null SD
Was playing with sched_smt_power_savings/sched_mc_power_savings and found
out that while the scheduler domains are reconstructed when sysfs settings
change, rebalance_domains() can get triggered with null domain on other cpus,
which is setting next_balance to jiffies + 60*HZ. Resulting in no idle/busy
balancing for 60 seconds.
Fix this.
Signed-off-by: Suresh Siddha [EMAIL PROTECTED]
---
diff --git a/kernel/sched.c b/kernel/sched.c
index 45e17b8..74565c0 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3020,6 +3020,7 @@ static inline void rebalance_domains(int cpu, enum
cpu_idle_type idle)
struct sched_domain *sd;
/* Earliest time when we have to do rebalance again */
unsigned long next_balance = jiffies + 60*HZ;
+ int update_next_balance = 0;
for_each_domain(cpu, sd) {
if (!(sd-flags SD_LOAD_BALANCE))
@@ -3056,8 +3057,10 @@ static inline void rebalance_domains(int cpu, enum
cpu_idle_type idle)
if (sd-flags SD_SERIALIZE)
spin_unlock(balancing);
out:
- if (time_after(next_balance, sd-last_balance + interval))
+ if (time_after(next_balance, sd-last_balance + interval)) {
next_balance = sd-last_balance + interval;
+ update_next_balance = 1;
+ }
/*
* Stop the load balance at this level. There is another
@@ -3067,7 +3070,14 @@ out:
if (!balance)
break;
}
- rq-next_balance = next_balance;
+
+ /*
+* next_balance will be updated only when there is a need.
+* When the cpu is attached to null domain for ex, it will not be
+* updated.
+*/
+ if (likely(update_next_balance))
+ rq-next_balance = next_balance;
}
/*
-
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