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Date: Thu, 07 Jan 2010 16:45:03 +0800
From: Lin Ming <ming.m.lin@...el.com>
To: Mike Galbraith <efault@....de>
Cc: Peter Zijlstra <peterz@...radead.org>,
lkml <linux-kernel@...r.kernel.org>,
"Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>
Subject: Re: [RFC PATCH] sched: Pass affine target cpu into wake_affine
On Tue, 2010-01-05 at 14:43 +0800, Mike Galbraith wrote:
> On Tue, 2010-01-05 at 04:44 +0100, Mike Galbraith wrote:
> > On Tue, 2010-01-05 at 10:48 +0800, Lin Ming wrote:
> > > On Mon, 2010-01-04 at 17:03 +0800, Lin Ming wrote:
> > > > commit a03ecf08d7bbdd979d81163ea13d194fe21ad339
> > > > Author: Lin Ming <ming.m.lin@...el.com>
> > > > Date: Mon Jan 4 14:14:50 2010 +0800
> > > >
> > > > sched: Pass affine target cpu into wake_affine
> > > >
> > > > Since commit a1f84a3(sched: Check for an idle shared cache in select_task_rq_fair()),
> > > > the affine target maybe adjusted to any idle cpu in cache sharing domains
> > > > instead of current cpu.
> > > > But wake_affine still use current cpu to calculate load which is wrong.
> > > >
> > > > This patch passes affine cpu into wake_affine.
> > > >
> > > > Signed-off-by: Lin Ming <ming.m.lin@...el.com>
> > >
> > > Mike,
> > >
> > > Any comment of this patch?
> >
> > The patch definitely looks like the right thing to do, but when I tried
> > this, it didn't work out well. Since I can't seem to recall precise
> > details, I'll let my box either remind me or give it's ack.
>
> Unfortunately, box reminded me. mysql+oltp peak throughput with
> nr_clients == nr_cpus
Did you test with your vmark regression fix patch also applied?
I tested on below 2 machines with the 2 patches both applied and the
oltp(sysbench+mysql) data shows good.
Tigerton x86_64 machine: 16cpus(4P/4Cores), 40G mem
IA64 machine: 32cpus(4P/4Cores/HT), 16G mem
Compared with upstream 2.6.33-rc2, IA64 improves ~15% and Tigerton
improves ~3%.
The 2 patches are merged as below,
diff --git a/include/linux/topology.h b/include/linux/topology.h
index 57e6357..5b81156 100644
--- a/include/linux/topology.h
+++ b/include/linux/topology.h
@@ -99,7 +99,7 @@ int arch_update_cpu_topology(void);
| 1*SD_WAKE_AFFINE \
| 1*SD_SHARE_CPUPOWER \
| 0*SD_POWERSAVINGS_BALANCE \
- | 0*SD_SHARE_PKG_RESOURCES \
+ | 1*SD_SHARE_PKG_RESOURCES \
| 0*SD_SERIALIZE \
| 0*SD_PREFER_SIBLING \
, \
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 42ac3c9..cbf4bd2 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1237,11 +1237,11 @@ static inline unsigned long effective_load(struct task_group *tg, int cpu,
#endif
-static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
+static int wake_affine(struct sched_domain *sd, struct task_struct *p, int affine_cpu, int sync)
{
struct task_struct *curr = current;
- unsigned long this_load, load;
- int idx, this_cpu, prev_cpu;
+ unsigned long affine_load, load;
+ int idx, prev_cpu;
unsigned long tl_per_task;
unsigned int imbalance;
struct task_group *tg;
@@ -1249,10 +1249,9 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
int balanced;
idx = sd->wake_idx;
- this_cpu = smp_processor_id();
prev_cpu = task_cpu(p);
load = source_load(prev_cpu, idx);
- this_load = target_load(this_cpu, idx);
+ affine_load = target_load(affine_cpu, idx);
if (sync) {
if (sched_feat(SYNC_LESS) &&
@@ -1275,7 +1274,7 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
tg = task_group(current);
weight = current->se.load.weight;
- this_load += effective_load(tg, this_cpu, -weight, -weight);
+ affine_load += effective_load(tg, affine_cpu, -weight, -weight);
load += effective_load(tg, prev_cpu, 0, -weight);
}
@@ -1285,16 +1284,16 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
imbalance = 100 + (sd->imbalance_pct - 100) / 2;
/*
- * In low-load situations, where prev_cpu is idle and this_cpu is idle
- * due to the sync cause above having dropped this_load to 0, we'll
+ * In low-load situations, where prev_cpu is idle and affine_cpu is idle
+ * due to the sync cause above having dropped affine_load to 0, we'll
* always have an imbalance, but there's really nothing you can do
* about that, so that's good too.
*
* Otherwise check if either cpus are near enough in load to allow this
- * task to be woken on this_cpu.
+ * task to be woken on affine_cpu.
*/
- balanced = !this_load ||
- 100*(this_load + effective_load(tg, this_cpu, weight, weight)) <=
+ balanced = !affine_load ||
+ 100*(affine_load + effective_load(tg, affine_cpu, weight, weight)) <=
imbalance*(load + effective_load(tg, prev_cpu, 0, weight));
/*
@@ -1306,11 +1305,11 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
return 1;
schedstat_inc(p, se.nr_wakeups_affine_attempts);
- tl_per_task = cpu_avg_load_per_task(this_cpu);
+ tl_per_task = cpu_avg_load_per_task(affine_cpu);
if (balanced ||
- (this_load <= load &&
- this_load + target_load(prev_cpu, idx) <= tl_per_task)) {
+ (affine_load <= load &&
+ affine_load + target_load(prev_cpu, idx) <= tl_per_task)) {
/*
* This domain has SD_WAKE_AFFINE and
* p is cache cold in this domain, and
@@ -1508,7 +1507,7 @@ static int select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flag
* If there's an idle sibling in this domain, make that
* the wake_affine target instead of the current cpu.
*/
- if (tmp->flags & SD_PREFER_SIBLING)
+ if (tmp->flags & SD_SHARE_PKG_RESOURCES)
target = select_idle_sibling(p, tmp, target);
if (target >= 0) {
@@ -1544,7 +1543,7 @@ static int select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flag
update_shares(tmp);
}
- if (affine_sd && wake_affine(affine_sd, p, sync))
+ if (affine_sd && wake_affine(affine_sd, p, cpu, sync))
return cpu;
while (sd) {
--
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