[PATCH 19/19] sched/numa: Move task_placement closer to numa_migrate_preferred

Srikar Dronamraju
2018-06-04T10:01:44Z

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.

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@linux.vnet.ibm.com>
---
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 fc1f388..fe0a5cf 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2183,9 +2183,6 @@ 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]);
@@ -2388,14 +2385,14 @@ 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;
--
1.8.3.1