This is a note to let you know that I've just added the patch titled
sched/numa: Trace decisions related to skipping VMAs
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
sched-numa-trace-decisions-related-to-skipping-vmas.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit cca0ec561a59223e0cdfc1ba489f060cb4ab286b
Author: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Date: Tue Oct 10 09:31:40 2023 +0100
sched/numa: Trace decisions related to skipping VMAs
[ Upstream commit ed2da8b725b932b1e2b2f4835bb664d47ed03031 ]
NUMA balancing skips or scans VMAs for a variety of reasons. In preparation
for completing scans of VMAs regardless of PID access, trace the reasons
why a VMA was skipped. In a later patch, the tracing will be used to track
if a VMA was forcibly scanned.
Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20231010083143.19593-4-mgorman@xxxxxxxxxxxxxxxxxxx
Stable-dep-of: f22cde4371f3 ("sched/numa: Fix the vma scan starving issue")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/include/linux/sched/numa_balancing.h b/include/linux/sched/numa_balancing.h
index 3988762efe15c..c127a1509e2fa 100644
--- a/include/linux/sched/numa_balancing.h
+++ b/include/linux/sched/numa_balancing.h
@@ -15,6 +15,14 @@
#define TNF_FAULT_LOCAL 0x08
#define TNF_MIGRATE_FAIL 0x10
+enum numa_vmaskip_reason {
+ NUMAB_SKIP_UNSUITABLE,
+ NUMAB_SKIP_SHARED_RO,
+ NUMAB_SKIP_INACCESSIBLE,
+ NUMAB_SKIP_SCAN_DELAY,
+ NUMAB_SKIP_PID_INACTIVE,
+};
+
#ifdef CONFIG_NUMA_BALANCING
extern void task_numa_fault(int last_node, int node, int pages, int flags);
extern pid_t task_numa_group_id(struct task_struct *p);
diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index fbb99a61f714c..b0d0dbf491ea6 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -664,6 +664,56 @@ DEFINE_EVENT(sched_numa_pair_template, sched_swap_numa,
TP_ARGS(src_tsk, src_cpu, dst_tsk, dst_cpu)
);
+#ifdef CONFIG_NUMA_BALANCING
+#define NUMAB_SKIP_REASON \
+ EM( NUMAB_SKIP_UNSUITABLE, "unsuitable" ) \
+ EM( NUMAB_SKIP_SHARED_RO, "shared_ro" ) \
+ EM( NUMAB_SKIP_INACCESSIBLE, "inaccessible" ) \
+ EM( NUMAB_SKIP_SCAN_DELAY, "scan_delay" ) \
+ EMe(NUMAB_SKIP_PID_INACTIVE, "pid_inactive" )
+
+/* Redefine for export. */
+#undef EM
+#undef EMe
+#define EM(a, b) TRACE_DEFINE_ENUM(a);
+#define EMe(a, b) TRACE_DEFINE_ENUM(a);
+
+NUMAB_SKIP_REASON
+
+/* Redefine for symbolic printing. */
+#undef EM
+#undef EMe
+#define EM(a, b) { a, b },
+#define EMe(a, b) { a, b }
+
+TRACE_EVENT(sched_skip_vma_numa,
+
+ TP_PROTO(struct mm_struct *mm, struct vm_area_struct *vma,
+ enum numa_vmaskip_reason reason),
+
+ TP_ARGS(mm, vma, reason),
+
+ TP_STRUCT__entry(
+ __field(unsigned long, numa_scan_offset)
+ __field(unsigned long, vm_start)
+ __field(unsigned long, vm_end)
+ __field(enum numa_vmaskip_reason, reason)
+ ),
+
+ TP_fast_assign(
+ __entry->numa_scan_offset = mm->numa_scan_offset;
+ __entry->vm_start = vma->vm_start;
+ __entry->vm_end = vma->vm_end;
+ __entry->reason = reason;
+ ),
+
+ TP_printk("numa_scan_offset=%lX vm_start=%lX vm_end=%lX reason=%s",
+ __entry->numa_scan_offset,
+ __entry->vm_start,
+ __entry->vm_end,
+ __print_symbolic(__entry->reason, NUMAB_SKIP_REASON))
+);
+#endif /* CONFIG_NUMA_BALANCING */
/*
* Tracepoint for waking a polling cpu without an IPI.
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index d07fb0a0da808..7c5f6e94b3cdc 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3285,6 +3285,7 @@ static void task_numa_work(struct callback_head *work)
do {
if (!vma_migratable(vma) || !vma_policy_mof(vma) ||
is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_MIXEDMAP)) {
+ trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_UNSUITABLE);
continue;
}
@@ -3295,15 +3296,19 @@ static void task_numa_work(struct callback_head *work)
* as migrating the pages will be of marginal benefit.
*/
if (!vma->vm_mm ||
- (vma->vm_file && (vma->vm_flags & (VM_READ|VM_WRITE)) == (VM_READ)))
+ (vma->vm_file && (vma->vm_flags & (VM_READ|VM_WRITE)) == (VM_READ))) {
+ trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_SHARED_RO);
continue;
+ }
/*
* Skip inaccessible VMAs to avoid any confusion between
* PROT_NONE and NUMA hinting ptes
*/
- if (!vma_is_accessible(vma))
+ if (!vma_is_accessible(vma)) {
+ trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_INACCESSIBLE);
continue;
+ }
/* Initialise new per-VMA NUMAB state. */
if (!vma->numab_state) {
@@ -3325,12 +3330,16 @@ static void task_numa_work(struct callback_head *work)
* delay the scan for new VMAs.
*/
if (mm->numa_scan_seq && time_before(jiffies,
- vma->numab_state->next_scan))
+ vma->numab_state->next_scan)) {
+ trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_SCAN_DELAY);
continue;
+ }
/* Do not scan the VMA if task has not accessed */
- if (!vma_is_accessed(vma))
+ if (!vma_is_accessed(vma)) {
+ trace_sched_skip_vma_numa(mm, vma, NUMAB_SKIP_PID_INACTIVE);
continue;
+ }
/*
* RESET access PIDs regularly for old VMAs. Resetting after checking
