[DEBUG] Some additional VM counters
Add a few counters to be able to see how the softirq affects the
scheduler. This patch should not go into mainline and maybe also
not into mm.
New counters in /proc/vmstat
sched_tick_balance Ticks that required invokation of the softirq
sched_tick_no_balance Ticks that did not require the softirq
sched_load_balance # invocations of load_balance().
sched_balance_softirq # of softirq executions
sched_balance_running # of times that serialization prevented
load balancing of a sched_domain.
Signed-off-by: Christoph Lameter <[email protected]>
Index: linux-2.6.19-rc5-mm1/include/linux/vmstat.h
===================================================================
--- linux-2.6.19-rc5-mm1.orig/include/linux/vmstat.h 2006-11-13 19:04:08.000000000 -0600
+++ linux-2.6.19-rc5-mm1/include/linux/vmstat.h 2006-11-13 19:06:12.308571232 -0600
@@ -47,6 +47,8 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS
FOR_ALL_ZONES(PGSCAN_DIRECT),
PGINODESTEAL, SLABS_SCANNED, KSWAPD_STEAL, KSWAPD_INODESTEAL,
PAGEOUTRUN, ALLOCSTALL, PGROTATED,
+ SCHED_TICK_NO_BALANCE, SCHED_TICK_BALANCE, SCHED_BALANCE_SOFTIRQ,
+ SCHED_LOAD_BALANCE, SCHED_BALANCE_RUNNING,
NR_VM_EVENT_ITEMS
};
Index: linux-2.6.19-rc5-mm1/kernel/sched.c
===================================================================
--- linux-2.6.19-rc5-mm1.orig/kernel/sched.c 2006-11-13 19:06:01.000000000 -0600
+++ linux-2.6.19-rc5-mm1/kernel/sched.c 2006-11-13 19:06:12.405259200 -0600
@@ -2900,6 +2900,8 @@ static void run_rebalance_domains(struct
/* Earliest time when we have to call run_rebalance_domains again */
unsigned long next_balance = jiffies + 60*HZ;
+ __count_vm_event(SCHED_BALANCE_SOFTIRQ);
+
for_each_domain(this_cpu, sd) {
if (!(sd->flags & SD_LOAD_BALANCE))
continue;
@@ -2914,11 +2916,14 @@ static void run_rebalance_domains(struct
interval = 1;
if (sd->flags & SD_SERIALIZE) {
- if (!spin_trylock(&balancing))
+ if (!spin_trylock(&balancing)) {
+ __count_vm_event(SCHED_BALANCE_RUNNING);
goto out;
+ }
}
if (time_after_eq(jiffies, sd->last_balance + interval)) {
+ __count_vm_event(SCHED_LOAD_BALANCE);
if (load_balance(this_cpu, this_rq, sd, idle)) {
/*
* We've pulled tasks over so either we're no
@@ -3188,8 +3193,11 @@ void scheduler_tick(void)
task_running_tick(rq, p);
#ifdef CONFIG_SMP
update_load(rq);
- if (time_after_eq(jiffies, rq->next_balance))
+ if (time_after_eq(jiffies, rq->next_balance)) {
+ __count_vm_event(SCHED_TICK_BALANCE);
raise_softirq(SCHED_SOFTIRQ);
+ }
+ __count_vm_event(SCHED_TICK_NO_BALANCE);
#endif
}
Index: linux-2.6.19-rc5-mm1/mm/vmstat.c
===================================================================
--- linux-2.6.19-rc5-mm1.orig/mm/vmstat.c 2006-11-13 19:04:08.000000000 -0600
+++ linux-2.6.19-rc5-mm1/mm/vmstat.c 2006-11-13 19:06:12.560545937 -0600
@@ -509,6 +509,11 @@ static char *vmstat_text[] = {
"allocstall",
"pgrotated",
+ "sched_tick_no_balance",
+ "sched_tick_balance",
+ "sched_balance_softirq",
+ "sched_load_balance",
+ "sched_balance_running",
#endif
};
-
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