Re: [LKP] [sched/fair] 070f5e860e: reaim.jobs_per_min -10.5% regression
From: Xing Zhengjun
Date: Mon Jun 15 2020 - 23:24:13 EST
On 6/15/2020 11:10 PM, Hillf Danton wrote:
On Mon, 15 Jun 2020 10:10:41 +0200 Vincent Guittot wrote:
Le lundi 15 juin 2020 15:26:59 (+0800), Xing Zhengjun a crit :
On 6/12/2020 7:06 PM, Hillf Danton wrote:
On Fri, 12 Jun 2020 14:36:49 +0800 Xing Zhengjun wrote:
...
I apply the patch based on v5.7, the regression still existed.
Thanks for the test.
Thanks.
I don't know if it's relevant or not but the results seem a bit
better with the patch and I'd like to check that it's only a matter of threshold to
fix the problem.
Could you try the patch below which is quite aggressive but will help to confirm this ?
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 28be1c984a42..3c51d557547b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8322,10 +8322,13 @@ static inline int sg_imbalanced(struct sched_group *group)
static inline bool
group_has_capacity(unsigned int imbalance_pct, struct sg_lb_stats *sgs)
{
+ unsigned long imb;
+
if (sgs->sum_nr_running < sgs->group_weight)
return true;
- if ((sgs->group_capacity * imbalance_pct) <
+ imb = sgs->sum_nr_running * 100;
+ if ((sgs->group_capacity * imb) <
(sgs->group_runnable * 100))
return false;
@@ -8347,6 +8350,8 @@ group_has_capacity(unsigned int imbalance_pct, struct sg_lb_stats *sgs)
static inline bool
group_is_overloaded(unsigned int imbalance_pct, struct sg_lb_stats *sgs)
{
+ unsigned long imb;
+
if (sgs->sum_nr_running <= sgs->group_weight)
return false;
@@ -8354,7 +8359,8 @@ group_is_overloaded(unsigned int imbalance_pct, struct sg_lb_stats *sgs)
(sgs->group_util * imbalance_pct))
return true;
- if ((sgs->group_capacity * imbalance_pct) <
+ imb = sgs->sum_nr_running * 100;
+ if ((sgs->group_capacity * imb) <
(sgs->group_runnable * 100))
return true;
=========================================================================================
tbox_group/testcase/rootfs/kconfig/compiler/runtime/nr_task/debug-setup/test/cpufreq_governor/ucode:
lkp-ivb-d04/reaim/debian-x86_64-20191114.cgz/x86_64-rhel-7.6/gcc-7/300s/100%/test/five_sec/performance/0x21
commit:
9f68395333ad7f5bfe2f83473fed363d4229f11c
070f5e860ee2bf588c99ef7b4c202451faa48236
v5.7
6b33257768b8dd3982054885ea310871be2cfe0b (Hillf's patch)
9f68395333ad7f5b 070f5e860ee2bf588c99ef7b4c2 v5.7
6b33257768b8dd3982054885ea3
---------------- --------------------------- ---------------------------
---------------------------
%stddev %change %stddev %change %stddev %change
%stddev
\ | \ | \
| \
0.69 -10.3% 0.62 -9.1% 0.62
-10.1% 0.62 reaim.child_systime
0.62 -1.0% 0.61 +0.5% 0.62
+0.3% 0.62 reaim.child_utime
66870 -10.0% 60187 -7.6% 61787
-8.3% 61305 reaim.jobs_per_min
16717 -10.0% 15046 -7.6% 15446
-8.3% 15326 reaim.jobs_per_min_child
97.84 -1.1% 96.75 -0.4% 97.43
-0.5% 97.37 reaim.jti
72000 -10.8% 64216 -8.3% 66000
-8.3% 66000 reaim.max_jobs_per_min
0.36 +10.6% 0.40 +7.8% 0.39
+9.4% 0.39 reaim.parent_time
1.58 2% +71.0% 2.70 2% +26.9% 2.01 2%
+33.2% 2.11 reaim.std_dev_percent
0.00 5% +110.4% 0.01 3% +48.8% 0.01 7%
+65.3% 0.01 3% reaim.std_dev_time
50800 -2.4% 49600 -1.6% 50000
-1.8% 49866 reaim.workload
Following the introduction of runnable_avg there came a gap between it
and util, and it can be supposedly filled up by determining the pivot
point using the imb percent. The upside is that no heuristic is added.
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8215,15 +8215,8 @@ group_has_capacity(unsigned int imbalanc
if (sgs->sum_nr_running < sgs->group_weight)
return true;
- if ((sgs->group_capacity * imbalance_pct) <
- (sgs->group_runnable * 100))
- return false;
-
- if ((sgs->group_capacity * 100) >
- (sgs->group_util * imbalance_pct))
- return true;
-
- return false;
+ return sgs->group_capacity * imbalance_pct >
+ (sgs->group_util + sgs->group_runnable) *50;
}
/*
@@ -8240,15 +8233,8 @@ group_is_overloaded(unsigned int imbalan
if (sgs->sum_nr_running <= sgs->group_weight)
return false;
- if ((sgs->group_capacity * 100) <
- (sgs->group_util * imbalance_pct))
- return true;
-
- if ((sgs->group_capacity * imbalance_pct) <
- (sgs->group_runnable * 100))
- return true;
-
- return false;
+ return sgs->group_capacity * imbalance_pct <
+ (sgs->group_util + sgs->group_runnable) *50;
}
/*
I apply the patch based on v5.7, the test result is as the following:
=========================================================================================
tbox_group/testcase/rootfs/kconfig/compiler/runtime/nr_task/debug-setup/test/cpufreq_governor/ucode:
lkp-ivb-d04/reaim/debian-x86_64-20191114.cgz/x86_64-rhel-7.6/gcc-7/300s/100%/test/five_sec/performance/0x21
commit:
9f68395333ad7f5bfe2f83473fed363d4229f11c
070f5e860ee2bf588c99ef7b4c202451faa48236
v5.7
1d5ee1e6dab1f8903cd7219fbcc5ac2f728ac80c (the test patch)
9f68395333ad7f5b 070f5e860ee2bf588c99ef7b4c2 v5.7
1d5ee1e6dab1f8903cd7219fbcc
---------------- --------------------------- ---------------------------
---------------------------
%stddev %change %stddev %change
%stddev %change %stddev
\ | \ | \
| \
0.69 -10.3% 0.62 -9.1% 0.62
-6.8% 0.64 reaim.child_systime
0.62 -1.0% 0.61 +0.5% 0.62
+0.6% 0.62 reaim.child_utime
66870 -10.0% 60187 -7.6% 61787
-5.7% 63058 reaim.jobs_per_min
16717 -10.0% 15046 -7.6% 15446
-5.7% 15764 reaim.jobs_per_min_child
97.84 -1.1% 96.75 -0.4% 97.43
-0.5% 97.31 reaim.jti
72000 -10.8% 64216 -8.3% 66000
-5.7% 67885 reaim.max_jobs_per_min
0.36 +10.6% 0.40 +7.8% 0.39
+6.0% 0.38 reaim.parent_time
1.58 Â 2% +71.0% 2.70 Â 2% +26.9% 2.01 Â
2% +33.1% 2.10 Â 3% reaim.std_dev_percent
0.00 Â 5% +110.4% 0.01 Â 3% +48.8% 0.01 Â
7% +58.1% 0.01 Â 6% reaim.std_dev_time
50800 -2.4% 49600 -1.6% 50000
-0.8% 50400 reaim.workload
--
Zhengjun Xing