[tip:sched/core] sched/numa: Move task_numa_placement() closer to numa_migrate_preferred()

From: tip-bot for Srikar Dronamraju
Date: Wed Jul 25 2018 - 10:30:45 EST

Commit-ID: b6a60cf36d497e7fbde9dd5b86fabd96850249f6
Gitweb: https://git.kernel.org/tip/b6a60cf36d497e7fbde9dd5b86fabd96850249f6
Author: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
AuthorDate: Wed, 20 Jun 2018 22:33:00 +0530
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 25 Jul 2018 11:41:08 +0200

sched/numa: Move task_numa_placement() closer to numa_migrate_preferred()

numa_migrate_preferred() is called periodically or when task preferred
node changes. Preferred node evaluations happen once per scan sequence.

If the scan completion happens just after the periodic NUMA migration,
then we try to migrate to the preferred node and the preferred node might
change, needing another node migration.

Avoid this by checking for scan sequence completion only when checking
for periodic migration.

Running SPECjbb2005 on a 4 node machine and comparing bops/JVM
JVMS LAST_PATCH WITH_PATCH %CHANGE
16 25862.6 26158.1 1.14258
1 74357 72725 -2.19482

Running SPECjbb2005 on a 16 node machine and comparing bops/JVM
JVMS LAST_PATCH WITH_PATCH %CHANGE
8 117019 113992 -2.58
1 179095 174947 -2.31

(numbers from v1 based on v4.17-rc5)
Testcase Time: Min Max Avg StdDev
numa01.sh Real: 449.46 770.77 615.22 101.70
numa01.sh Sys: 132.72 208.17 170.46 24.96
numa01.sh User: 39185.26 60290.89 50066.76 6807.84
numa02.sh Real: 60.85 61.79 61.28 0.37
numa02.sh Sys: 15.34 24.71 21.08 3.61
numa02.sh User: 5204.41 5249.85 5231.21 17.60
numa03.sh Real: 785.50 916.97 840.77 44.98
numa03.sh Sys: 108.08 133.60 119.43 8.82
numa03.sh User: 61422.86 70919.75 64720.87 3310.61
numa04.sh Real: 429.57 587.37 480.80 57.40
numa04.sh Sys: 240.61 321.97 290.84 33.58
numa04.sh User: 34597.65 40498.99 37079.48 2060.72
numa05.sh Real: 392.09 431.25 414.65 13.82
numa05.sh Sys: 229.41 372.48 297.54 53.14
numa05.sh User: 33390.86 34697.49 34222.43 556.42

Testcase Time: Min Max Avg StdDev %Change
numa01.sh Real: 424.63 566.18 498.12 59.26 23.50%
numa01.sh Sys: 160.19 256.53 208.98 37.02 -18.4%
numa01.sh User: 37320.00 46225.58 42001.57 3482.45 19.20%
numa02.sh Real: 60.17 62.47 60.91 0.85 0.607%
numa02.sh Sys: 15.30 22.82 17.04 2.90 23.70%
numa02.sh User: 5202.13 5255.51 5219.08 20.14 0.232%
numa03.sh Real: 823.91 844.89 833.86 8.46 0.828%
numa03.sh Sys: 130.69 148.29 140.47 6.21 -14.9%
numa03.sh User: 62519.15 64262.20 63613.38 620.05 1.740%
numa04.sh Real: 515.30 603.74 548.56 30.93 -12.3%
numa04.sh Sys: 459.73 525.48 489.18 21.63 -40.5%
numa04.sh User: 40561.96 44919.18 42047.87 1526.85 -11.8%
numa05.sh Real: 396.58 454.37 421.13 19.71 -1.53%
numa05.sh Sys: 208.72 422.02 348.90 73.60 -14.7%
numa05.sh User: 33124.08 36109.35 34846.47 1089.74 -1.79%

Signed-off-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1529514181-9842-20-git-send-email-srikar@xxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/sched/fair.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 9c9e54ea65d9..309c93fcc604 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2180,9 +2180,6 @@ static void task_numa_placement(struct task_struct *p)
/* Set the new preferred node */
if (max_nid != p->numa_preferred_nid)
sched_setnuma(p, max_nid);
-
- if (task_node(p) != p->numa_preferred_nid)
- numa_migrate_preferred(p);
}

update_task_scan_period(p, fault_types[0], fault_types[1]);
@@ -2385,14 +2382,14 @@ void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags)
numa_is_active_node(mem_node, ng))
local = 1;

- task_numa_placement(p);
-
/*
* Retry task to preferred node migration periodically, in case it
* case it previously failed, or the scheduler moved us.
*/
- if (time_after(jiffies, p->numa_migrate_retry))
+ if (time_after(jiffies, p->numa_migrate_retry)) {
+ task_numa_placement(p);
numa_migrate_preferred(p);
+ }

if (migrated)
p->numa_pages_migrated += pages;