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Message-Id: <20230123173748.1734238-8-shr@devkernel.io>
Date: Mon, 23 Jan 2023 09:37:35 -0800
From: Stefan Roesch <shr@...kernel.io>
To: linux-mm@...ck.org
Cc: shr@...kernel.io, linux-doc@...r.kernel.org,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-kselftest@...r.kernel.org, linux-trace-kernel@...r.kernel.org
Subject: [RESEND RFC PATCH v1 07/20] mm: add tracepoints to ksm
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
Signed-off-by: Stefan Roesch <shr@...kernel.io>
---
MAINTAINERS | 1 +
include/trace/events/ksm.h | 257 +++++++++++++++++++++++++++++++++++++
mm/ksm.c | 20 ++-
3 files changed, 276 insertions(+), 2 deletions(-)
create mode 100644 include/trace/events/ksm.h
diff --git a/MAINTAINERS b/MAINTAINERS
index 123216b76534..990a28bdc263 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -13482,6 +13482,7 @@ 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/testing/selftests/vm/
diff --git a/include/trace/events/ksm.h b/include/trace/events/ksm.h
new file mode 100644
index 000000000000..727d8f6dbc3f
--- /dev/null
+++ b/include/trace/events/ksm.h
@@ -0,0 +1,257 @@
+/* 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
+ * @flag: specified flags
+ *
+ * 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, unsigned int flag),
+
+ TP_ARGS(mm, flag),
+
+ TP_STRUCT__entry(
+ __field(void *, mm)
+ __field(unsigned int, flag)
+ ),
+
+ TP_fast_assign(
+ __entry->mm = mm;
+ __entry->flag = flag;
+ ),
+
+ TP_printk("mm %p flag %u",
+ __entry->mm, __entry->flag)
+);
+
+/**
+ * ksm_enter - called after a new process has been added to ksm
+ *
+ * @mm: address of the mm object of the process
+ * @flag: specified flags
+ *
+ * Allows to trace the when a process has been added to ksm.
+ */
+DEFINE_EVENT(ksm_enter_exit_template, ksm_enter,
+
+ TP_PROTO(void *mm, unsigned int flag),
+
+ TP_ARGS(mm, flag)
+);
+
+/**
+ * ksm_exit - called after a new process has been removed from ksm
+ *
+ * @mm: address of the mm object of the process
+ * @flag: specified flags
+ *
+ * Allows to trace the when a process has been removed from ksm.
+ */
+DEFINE_EVENT(ksm_enter_exit_template, ksm_exit,
+
+ TP_PROTO(void *mm, unsigned int flag),
+
+ TP_ARGS(mm, flag)
+);
+
+/**
+ * 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>
diff --git a/mm/ksm.c b/mm/ksm.c
index 5fa6b46dfa3b..88a969849955 100644
--- a/mm/ksm.c
+++ 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)
@@ -633,10 +636,12 @@ 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) {
+ trace_ksm_remove_rmap_item(stable_node->kpfn, rmap_item, rmap_item->mm);
ksm_pages_sharing--;
- else
+ } else {
ksm_pages_shared--;
+ }
rmap_item->mm->ksm_merging_pages--;
@@ -657,6 +662,7 @@ 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
@@ -1319,6 +1325,8 @@ 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;
}
@@ -2137,6 +2145,8 @@ static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_ite
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);
} else {
/*
* If the vma is out of date, we do not need to
@@ -2270,6 +2280,8 @@ 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
@@ -2433,6 +2445,7 @@ 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;
}
@@ -2585,6 +2598,7 @@ int __ksm_enter(struct mm_struct *mm, int flag)
if (needs_wakeup)
wake_up_interruptible(&ksm_thread_wait);
+ trace_ksm_enter(mm, flag);
return 0;
}
@@ -2653,6 +2667,8 @@ void __ksm_exit(struct mm_struct *mm, int flag)
mmap_write_lock(mm);
mmap_write_unlock(mm);
}
+
+ trace_ksm_exit(mm, flag);
}
struct page *ksm_might_need_to_copy(struct page *page,
--
2.30.2
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