From 5c812a4d0da7cf62de09aaad65bd58c554d405f5 Mon Sep 17 00:00:00 2001
From: Mel Gorman <mgorman@techsingularity.net>
Date: Tue, 10 Oct 2023 09:31:38 +0100
Subject: [PATCH] sched/numa: Document vma_numab_state fields
References: bsc#1212887 (Scheduler functional and performance backports)
Git-commit: 9ae5c00ea2e600a8b823f9b95606dd244f3096bf
Patch-mainline: v6.7-rc1
Document the intended usage of the fields.
[ mingo: Reformatted to take less vertical space & tidied it up. ]
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20231010083143.19593-2-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
include/linux/mm_types.h | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index ac0c54728182..658c5eed8209 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -476,8 +476,29 @@ struct vma_lock {
};
struct vma_numab_state {
+ /*
+ * Initialised as time in 'jiffies' after which VMA
+ * should be scanned. Delays first scan of new VMA by at
+ * least sysctl_numa_balancing_scan_delay:
+ */
unsigned long next_scan;
+
+ /*
+ * Time in jiffies when access_pids[] is reset to
+ * detect phase change behaviour:
+ */
unsigned long next_pid_reset;
+
+ /*
+ * Approximate tracking of PIDs that trapped a NUMA hinting
+ * fault. May produce false positives due to hash collisions.
+ *
+ * [0] Previous PID tracking
+ * [1] Current PID tracking
+ *
+ * Window moves after next_pid_reset has expired approximately
+ * every VMA_PID_RESET_PERIOD jiffies:
+ */
unsigned long access_pids[2];
};