The patch titled
Subject: mm: add tracepoints to ksm
has been added to the -mm mm-unstable branch. Its filename is
mm-add-tracepoints-to-ksm.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-add-tracepoints-to-ksm.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Stefan Roesch <shr@xxxxxxxxxxxx>
Subject: mm: add tracepoints to ksm
Date: Fri, 10 Feb 2023 13:46:45 -0800
This adds the following tracepoints to ksm:
- start / stop scan
- ksm enter / exit
- merge a page
- merge a page with ksm
- remove a page
- remove a rmap item
This patch has been split off from the RFC patch series "mm:
process/cgroup ksm support".
Link: https://lkml.kernel.org/r/20230210214645.2720847-1-shr@xxxxxxxxxxxx
Signed-off-by: Stefan Roesch <shr@xxxxxxxxxxxx>
Reviewed-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
new file mode 100644
--- /dev/null
+++ b/include/trace/events/ksm.h
@@ -0,0 +1,251 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM ksm
+
+#if !defined(_TRACE_KSM_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_KSM_H
+
+#include <linux/tracepoint.h>
+
+/**
+ * ksm_scan_template - called for start / stop scan
+ *
+ * @seq: sequence number of scan
+ * @rmap_entries: actual number of rmap entries
+ *
+ * Allows to trace the start / stop of a ksm scan.
+ */
+DECLARE_EVENT_CLASS(ksm_scan_template,
+
+ TP_PROTO(int seq, u32 rmap_entries),
+
+ TP_ARGS(seq, rmap_entries),
+
+ TP_STRUCT__entry(
+ __field(int, seq)
+ __field(u32, rmap_entries)
+ ),
+
+ TP_fast_assign(
+ __entry->seq = seq;
+ __entry->rmap_entries = rmap_entries;
+ ),
+
+ TP_printk("seq %d rmap size %d",
+ __entry->seq, __entry->rmap_entries)
+);
+
+/**
+ * ksm_start_scan - called after a new ksm scan is started
+ *
+ * @seq: sequence number of scan
+ * @rmap_entries: actual number of rmap entries
+ *
+ * Allows to trace the start of a ksm scan.
+ */
+DEFINE_EVENT(ksm_scan_template, ksm_start_scan,
+
+ TP_PROTO(int seq, u32 rmap_entries),
+
+ TP_ARGS(seq, rmap_entries)
+);
+
+/**
+ * ksm_stop_scan - called after a new ksm scan has completed
+ *
+ * @seq: sequence number of scan
+ * @rmap_entries: actual number of rmap entries
+ *
+ * Allows to trace the completion of a ksm scan.
+ */
+DEFINE_EVENT(ksm_scan_template, ksm_stop_scan,
+
+ TP_PROTO(int seq, u32 rmap_entries),
+
+ TP_ARGS(seq, rmap_entries)
+);
+
+/**
+ * ksm_enter - called after a new process has been added / removed from ksm
+ *
+ * @mm: address of the mm object of the process
+ *
+ * Allows to trace the when a process has been added or removed from ksm.
+ */
+DECLARE_EVENT_CLASS(ksm_enter_exit_template,
+
+ TP_PROTO(void *mm),
+
+ TP_ARGS(mm),
+
+ TP_STRUCT__entry(
+ __field(void *, mm)
+ ),
+
+ TP_fast_assign(
+ __entry->mm = mm;
+ ),
+
+ TP_printk("mm %p", __entry->mm)
+);
+
+/**
+ * ksm_enter - called after a new process has been added to ksm
+ *
+ * @mm: address of the mm object of the process
+ *
+ * Allows to trace the when a process has been added to ksm.
+ */
+DEFINE_EVENT(ksm_enter_exit_template, ksm_enter,
+
+ TP_PROTO(void *mm),
+
+ TP_ARGS(mm)
+);
+
+/**
+ * ksm_exit - called after a new process has been removed from ksm
+ *
+ * @mm: address of the mm object of the process
+ *
+ * Allows to trace the when a process has been removed from ksm.
+ */
+DEFINE_EVENT(ksm_enter_exit_template, ksm_exit,
+
+ TP_PROTO(void *mm),
+
+ TP_ARGS(mm)
+);
+
+/**
+ * ksm_merge_one_page - called after a page has been merged
+ *
+ * @pfn: page frame number of ksm page
+ * @rmap_item: address of rmap_item object
+ * @mm: address of the process mm struct
+ * @err: success
+ *
+ * Allows to trace the ksm merging of individual pages.
+ */
+TRACE_EVENT(ksm_merge_one_page,
+
+ TP_PROTO(unsigned long pfn, void *rmap_item, void *mm, int err),
+
+ TP_ARGS(pfn, rmap_item, mm, err),
+
+ TP_STRUCT__entry(
+ __field(unsigned long, pfn)
+ __field(void *, rmap_item)
+ __field(void *, mm)
+ __field(int, err)
+ ),
+
+ TP_fast_assign(
+ __entry->pfn = pfn;
+ __entry->rmap_item = rmap_item;
+ __entry->mm = mm;
+ __entry->err = err;
+ ),
+
+ TP_printk("ksm pfn %lu rmap_item %p mm %p error %d",
+ __entry->pfn, __entry->rmap_item, __entry->mm, __entry->err)
+);
+
+/**
+ * ksm_merge_with_ksm_page - called after a page has been merged with a ksm page
+ *
+ * @ksm_page: address ksm page
+ * @pfn: page frame number of ksm page
+ * @rmap_item: address of rmap_item object
+ * @mm: address of the mm object of the process
+ * @err: success
+ *
+ * Allows to trace the merging of a page with a ksm page.
+ */
+TRACE_EVENT(ksm_merge_with_ksm_page,
+
+ TP_PROTO(void *ksm_page, unsigned long pfn, void *rmap_item, void *mm, int err),
+
+ TP_ARGS(ksm_page, pfn, rmap_item, mm, err),
+
+ TP_STRUCT__entry(
+ __field(void *, ksm_page)
+ __field(unsigned long, pfn)
+ __field(void *, rmap_item)
+ __field(void *, mm)
+ __field(int, err)
+ ),
+
+ TP_fast_assign(
+ __entry->ksm_page = ksm_page;
+ __entry->pfn = pfn;
+ __entry->rmap_item = rmap_item;
+ __entry->mm = mm;
+ __entry->err = err;
+ ),
+
+ TP_printk("%spfn %lu rmap_item %p mm %p error %d",
+ (__entry->ksm_page ? "ksm " : ""),
+ __entry->pfn, __entry->rmap_item, __entry->mm, __entry->err)
+);
+
+/**
+ * ksm_remove_ksm_page - called after a ksm page has been removed
+ *
+ * @pfn: page frame number of ksm page
+ *
+ * Allows to trace the removing of stable ksm pages.
+ */
+TRACE_EVENT(ksm_remove_ksm_page,
+
+ TP_PROTO(unsigned long pfn),
+
+ TP_ARGS(pfn),
+
+ TP_STRUCT__entry(
+ __field(unsigned long, pfn)
+ ),
+
+ TP_fast_assign(
+ __entry->pfn = pfn;
+ ),
+
+ TP_printk("pfn %lu", __entry->pfn)
+);
+
+/**
+ * ksm_remove_rmap_item - called after a rmap_item has been removed from the
+ * stable tree
+ *
+ * @pfn: page frame number of ksm page
+ * @rmap_item: address of rmap_item object
+ * @mm: address of the process mm struct
+ *
+ * Allows to trace the removal of pages from the stable tree list.
+ */
+TRACE_EVENT(ksm_remove_rmap_item,
+
+ TP_PROTO(unsigned long pfn, void *rmap_item, void *mm),
+
+ TP_ARGS(pfn, rmap_item, mm),
+
+ TP_STRUCT__entry(
+ __field(unsigned long, pfn)
+ __field(void *, rmap_item)
+ __field(void *, mm)
+ ),
+
+ TP_fast_assign(
+ __entry->pfn = pfn;
+ __entry->rmap_item = rmap_item;
+ __entry->mm = mm;
+ ),
+
+ TP_printk("pfn %lu rmap_item %p mm %p",
+ __entry->pfn, __entry->rmap_item, __entry->mm)
+);
+
+#endif /* _TRACE_KSM_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
--- a/MAINTAINERS~mm-add-tracepoints-to-ksm
+++ b/MAINTAINERS
@@ -13415,6 +13415,7 @@ F: include/linux/memory_hotplug.h
F: include/linux/mm.h
F: include/linux/mmzone.h
F: include/linux/pagewalk.h
+F: include/trace/events/ksm.h
F: mm/
F: tools/mm/
F: tools/testing/selftests/mm/
--- a/mm/ksm.c~mm-add-tracepoints-to-ksm
+++ b/mm/ksm.c
@@ -45,6 +45,9 @@
#include "internal.h"
#include "mm_slot.h"
+#define CREATE_TRACE_POINTS
+#include <trace/events/ksm.h>
+
#ifdef CONFIG_NUMA
#define NUMA(x) (x)
#define DO_NUMA(x) do { (x); } while (0)
@@ -655,10 +658,12 @@ static void remove_node_from_stable_tree(struct ksm_stable_node *stable_node)
BUG_ON(stable_node->rmap_hlist_len < 0);
hlist_for_each_entry(rmap_item, &stable_node->hlist, hlist) {
- if (rmap_item->hlist.next)
+ if (rmap_item->hlist.next) {
ksm_pages_sharing--;
- else
+ trace_ksm_remove_rmap_item(stable_node->kpfn, rmap_item, rmap_item->mm);
+ } else {
ksm_pages_shared--;
+ }
rmap_item->mm->ksm_merging_pages--;
@@ -679,6 +684,7 @@ static void remove_node_from_stable_tree(struct ksm_stable_node *stable_node)
BUILD_BUG_ON(STABLE_NODE_DUP_HEAD <= &migrate_nodes);
BUILD_BUG_ON(STABLE_NODE_DUP_HEAD >= &migrate_nodes + 1);
+ trace_ksm_remove_ksm_page(stable_node->kpfn);
if (stable_node->head == &migrate_nodes)
list_del(&stable_node->list);
else
@@ -1367,6 +1373,8 @@ static int try_to_merge_with_ksm_page(struct ksm_rmap_item *rmap_item,
get_anon_vma(vma->anon_vma);
out:
mmap_read_unlock(mm);
+ trace_ksm_merge_with_ksm_page(kpage, page_to_pfn(kpage ? kpage : page),
+ rmap_item, mm, err);
return err;
}
@@ -2114,6 +2122,9 @@ static int try_to_merge_with_kernel_zero_page(struct ksm_rmap_item *rmap_item,
if (vma) {
err = try_to_merge_one_page(vma, page,
ZERO_PAGE(rmap_item->address));
+ trace_ksm_merge_one_page(
+ page_to_pfn(ZERO_PAGE(rmap_item->address)),
+ rmap_item, mm, err);
if (!err) {
rmap_item->address |= ZERO_PAGE_FLAG;
ksm_zero_pages_sharing++;
@@ -2346,6 +2357,8 @@ static struct ksm_rmap_item *scan_get_next_rmap_item(struct page **page)
mm_slot = ksm_scan.mm_slot;
if (mm_slot == &ksm_mm_head) {
+ trace_ksm_start_scan(ksm_scan.seqnr, ksm_rmap_items);
+
/*
* A number of pages can hang around indefinitely on per-cpu
* pagevecs, raised page count preventing write_protect_page
@@ -2512,6 +2525,7 @@ static struct ksm_rmap_item *scan_get_next_rmap_item(struct page **page)
if (mm_slot != &ksm_mm_head)
goto next_mm;
+ trace_ksm_stop_scan(ksm_scan.seqnr, ksm_rmap_items);
ksm_scan.seqnr++;
return NULL;
}
@@ -2663,6 +2677,7 @@ int __ksm_enter(struct mm_struct *mm)
if (needs_wakeup)
wake_up_interruptible(&ksm_thread_wait);
+ trace_ksm_enter(mm);
return 0;
}
@@ -2704,6 +2719,8 @@ void __ksm_exit(struct mm_struct *mm)
mmap_write_lock(mm);
mmap_write_unlock(mm);
}
+
+ trace_ksm_exit(mm);
}
struct page *ksm_might_need_to_copy(struct page *page,
_
Patches currently in -mm which might be from shr@xxxxxxxxxxxx are
mm-add-new-ksm-process-and-sysfs-knobs.patch
selftests-mm-add-new-selftests-for-ksm.patch
mm-add-tracepoints-to-ksm.patch
