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s390/vtime: steal time exponential moving average

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To be able to judge the current overcommitment ratio for a CPU add
a lowcore field with the exponential moving average of the steal time.
The average is updated every tick.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky
2019-03-06 13:31:21 +02:00
parent 01396a374c
commit 152e9b8676
3 changed files with 45 additions and 38 deletions
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3
arch/s390/kernel/smp.c
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@@ -266,7 +266,8 @@ static void pcpu_prepare_secondary(struct pcpu *pcpu, int cpu)
lc->percpu_offset = __per_cpu_offset[cpu];
lc->kernel_asce = S390_lowcore.kernel_asce;
lc->machine_flags = S390_lowcore.machine_flags;
lc->user_timer = lc->system_timer = lc->steal_timer = 0;
lc->user_timer = lc->system_timer =
lc->steal_timer = lc->avg_steal_timer = 0;
__ctl_store(lc->cregs_save_area, 0, 15);
save_access_regs((unsigned int *) lc->access_regs_save_area);
memcpy(lc->stfle_fac_list, S390_lowcore.stfle_fac_list,

19
arch/s390/kernel/vtime.c
View File

@@ -124,7 +124,7 @@ static void account_system_index_scaled(struct task_struct *p, u64 cputime,
*/
static int do_account_vtime(struct task_struct *tsk)
{
u64 timer, clock, user, guest, system, hardirq, softirq, steal;
u64 timer, clock, user, guest, system, hardirq, softirq;
timer = S390_lowcore.last_update_timer;
clock = S390_lowcore.last_update_clock;
@@ -182,12 +182,6 @@ static int do_account_vtime(struct task_struct *tsk)
if (softirq)
account_system_index_scaled(tsk, softirq, CPUTIME_SOFTIRQ);
steal = S390_lowcore.steal_timer;
if ((s64) steal > 0) {
S390_lowcore.steal_timer = 0;
account_steal_time(cputime_to_nsecs(steal));
}
return virt_timer_forward(user + guest + system + hardirq + softirq);
}
@@ -213,8 +207,19 @@ void vtime_task_switch(struct task_struct *prev)
*/
void vtime_flush(struct task_struct *tsk)
{
u64 steal, avg_steal;
if (do_account_vtime(tsk))
virt_timer_expire();
steal = S390_lowcore.steal_timer;
avg_steal = S390_lowcore.avg_steal_timer / 2;
if ((s64) steal > 0) {
S390_lowcore.steal_timer = 0;
account_steal_time(steal);
avg_steal += steal;
}
S390_lowcore.avg_steal_timer = avg_steal;
}
/*