[PATCH 1/6] sched/numa: Document vma_numab_state fields

Mel Gorman
2023-10-10T08:32:16Z

Document the intended usage of the fields.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
---
include/linux/mm_types.h | 30 +++++++++++++++++++++++++++---
1 file changed, 27 insertions(+), 3 deletions(-)

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 36c5b43999e6..0fe054afc4d6 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -551,9 +551,33 @@ struct vma_lock {
};

struct vma_numab_state {
- unsigned long next_scan;
- unsigned long next_pid_reset;
- unsigned long access_pids[2];
+ unsigned long next_scan; /* 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_pid_reset; /* Time in jiffies when
+ * access_pids is reset to
+ * detect phase change
+ * behaviour.
+ */
+ unsigned long access_pids[2]; /* 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.
+ */
};

/*
--
2.35.3