[PATCH v4 0/2] mm/damon/vaddr: support stat-purpose DAMOS filters

[PATCH v4 0/2] mm/damon/vaddr: support stat-purpose DAMOS filters

[Yueyang Pan]

Extend DAMOS_STAT handling of the DAMON operations sets for virtual
address spaces for ops-level DAMOS filters.

Functionality Test
==================
I wrote a small test program which allocates 10GB of DRAM, use 
madvise(MADV_HUGEPAGE) to convert the base pages to 2MB huge pages
Then my program does the following things in order:
1. Write sequentially to the whole 10GB region
2. Read the first 5GB region sequentially for 10 times
3. Sleep 5s
4. Read the second 5GB region sequentially for 10 times

With a proper damon setting, we are expected to see df-passed to be 10GB
and hot region move around with the read

$ # Start DAMON
$ sudo ./damo/damo start "./my_test/test" --monitoring_intervals 100ms\
1s 2s

$ # Show DAMON-generated access pattern snapshot
$ sudo ./damo/damo report access --snapshot_damos_filter allow \
hugepage_size 2MiB 2MiB
    heatmap:
    # min/max temperatures: -600,000,000, 100,001,000, column size: 137.352 MiB
    intervals: sample 100 ms aggr 1 s (max access hz 10)
    # damos filters (df): reject none hugepage_size [2.000 MiB, 2.000 MiB]
    df-pass:
    # min/max temperatures: -400,000,000, 100,001,000, column size: 128.031 MiB
    0   addr 85.373 TiB   size 745.555 MiB access 0 hz   age 6 s           df-passed 0 B
    1   addr 127.608 TiB  size 877.664 MiB access 3.000 hz age 0 ns          df-passed 878.000 MiB
    2   addr 127.609 TiB  size 219.418 MiB access 2.000 hz age 0 ns          df-passed 220.000 MiB
    3   addr 127.609 TiB  size 316.613 MiB access 1.000 hz age 1 s           df-passed 316.000 MiB
    4   addr 127.609 TiB  size 474.922 MiB access 1.000 hz age 1 s           df-passed 476.000 MiB
    5   addr 127.610 TiB  size 407.188 MiB access 1.000 hz age 0 ns          df-passed 406.000 MiB
    6   addr 127.610 TiB  size 610.781 MiB access 1.000 hz age 0 ns          df-passed 612.000 MiB
    7   addr 127.611 TiB  size 697.309 MiB access 0 hz   age 0 ns          df-passed 696.000 MiB
    8   addr 127.611 TiB  size 77.480 MiB  access 1.000 hz age 0 ns          df-passed 78.000 MiB
    9   addr 127.611 TiB  size 573.102 MiB access 1.000 hz age 0 ns          df-passed 574.000 MiB
    10  addr 127.612 TiB  size 245.617 MiB access 2.000 hz age 0 ns          df-passed 246.000 MiB
    11  addr 127.612 TiB  size 295.102 MiB access 1.000 hz age 1 s           df-passed 294.000 MiB
    12  addr 127.612 TiB  size 295.105 MiB access 1.000 hz age 1 s           df-passed 296.000 MiB
    13  addr 127.613 TiB  size 67.172 MiB  access 1.000 hz age 1 s           df-passed 66.000 MiB
    14  addr 127.613 TiB  size 604.570 MiB access 0 hz   age 1 s           df-passed 606.000 MiB
    15  addr 127.613 TiB  size 389.578 MiB access 0 hz   age 4 s           df-passed 388.000 MiB
    16  addr 127.614 TiB  size 259.719 MiB access 0 hz   age 4 s           df-passed 260.000 MiB
    17  addr 127.614 TiB  size 817.941 MiB access 0 hz   age 4 s           df-passed 818.000 MiB
    18  addr 127.615 TiB  size 204.488 MiB access 0 hz   age 4 s           df-passed 204.000 MiB
    19  addr 127.615 TiB  size 730.902 MiB access 0 hz   age 4 s           df-passed 732.000 MiB
    20  addr 127.616 TiB  size 182.727 MiB access 0 hz   age 4 s           df-passed 182.000 MiB
    21  addr 127.616 TiB  size 926.824 MiB access 0 hz   age 2 s           df-passed 928.000 MiB
    22  addr 127.617 TiB  size 102.984 MiB access 0 hz   age 2 s           df-passed 102.000 MiB
    23  addr 127.617 TiB  size 86.527 MiB  access 0 hz   age 2 s           df-passed 86.000 MiB
    24  addr 127.617 TiB  size 778.777 MiB access 0 hz   age 2 s           df-passed 776.000 MiB
    25  addr 127.999 TiB  size 132.000 KiB access 0 hz   age 6 s           df-passed 0 B
    memory bw estimate: 6.524 GiB per second  df-passed: 6.527 GiB per second
    total size: 10.731 GiB  df-passed 10.000 GiB
    record DAMON intervals: sample 100 ms, aggr 1 s


$ # Show DAMON-generated access pattern snapshot again
$ sudo ./damo/damo report access --snapshot_damos_filter allow \
hugepage_size 2MiB 2MiB
    heatmap:
    # min/max temperatures: -1,100,000,000, 2,000, column size: 137.352 MiB
    intervals: sample 100 ms aggr 1 s (max access hz 10)
    # damos filters (df): reject none hugepage_size [2.000 MiB, 2.000 MiB]
    df-pass:
    # min/max temperatures: -900,000,000, 2,000, column size: 128.031 MiB
    0   addr 85.373 TiB   size 745.555 MiB access 0 hz   age 11 s          df-passed 0 B
    1   addr 127.608 TiB  size 579.715 MiB access 2.000 hz age 0 ns          df-passed 580.000 MiB
    2   addr 127.608 TiB  size 144.930 MiB access 2.000 hz age 0 ns          df-passed 146.000 MiB
    3   addr 127.608 TiB  size 452.453 MiB access 2.000 hz age 0 ns          df-passed 452.000 MiB
    4   addr 127.609 TiB  size 113.117 MiB access 1.000 hz age 0 ns          df-passed 114.000 MiB
    5   addr 127.609 TiB  size 182.367 MiB access 2.000 hz age 0 ns          df-passed 182.000 MiB
    6   addr 127.609 TiB  size 182.371 MiB access 2.000 hz age 0 ns          df-passed 182.000 MiB
    7   addr 127.609 TiB  size 350.488 MiB access 1.000 hz age 0 ns          df-passed 350.000 MiB
    8   addr 127.610 TiB  size 525.738 MiB access 1.000 hz age 0 ns          df-passed 526.000 MiB
    9   addr 127.610 TiB  size 401.352 MiB access 1.000 hz age 0 ns          df-passed 402.000 MiB
    10  addr 127.611 TiB  size 100.340 MiB access 1.000 hz age 0 ns          df-passed 100.000 MiB
    11  addr 127.611 TiB  size 19.523 MiB  access 0 hz   age 0 ns          df-passed 20.000 MiB
    12  addr 127.611 TiB  size 175.727 MiB access 0 hz   age 0 ns          df-passed 176.000 MiB
    13  addr 127.611 TiB  size 106.629 MiB access 0 hz   age 0 ns          df-passed 106.000 MiB
    14  addr 127.611 TiB  size 959.676 MiB access 0 hz   age 0 ns          df-passed 960.000 MiB
    15  addr 127.612 TiB  size 424.469 MiB access 1.000 hz age 0 ns          df-passed 424.000 MiB
    16  addr 127.612 TiB  size 424.469 MiB access 1.000 hz age 0 ns          df-passed 424.000 MiB
    17  addr 127.613 TiB  size 201.648 MiB access 0 hz   age 6 s           df-passed 202.000 MiB
    18  addr 127.613 TiB  size 806.609 MiB access 0 hz   age 6 s           df-passed 806.000 MiB
    19  addr 127.614 TiB  size 862.125 MiB access 0 hz   age 9 s           df-passed 862.000 MiB
    20  addr 127.614 TiB  size 215.535 MiB access 0 hz   age 9 s           df-passed 216.000 MiB
    21  addr 127.615 TiB  size 104.500 MiB access 0 hz   age 9 s           df-passed 104.000 MiB
    22  addr 127.615 TiB  size 940.523 MiB access 0 hz   age 9 s           df-passed 942.000 MiB
    23  addr 127.616 TiB  size 640.281 MiB access 0 hz   age 7 s           df-passed 640.000 MiB
    24  addr 127.616 TiB  size 426.855 MiB access 0 hz   age 7 s           df-passed 426.000 MiB
    25  addr 127.617 TiB  size 90.105 MiB  access 0 hz   age 7 s           df-passed 90.000 MiB
    26  addr 127.617 TiB  size 810.965 MiB access 0 hz   age 7 s           df-passed 808.000 MiB
    27  addr 127.999 TiB  size 132.000 KiB access 0 hz   age 11 s          df-passed 0 B
    memory bw estimate: 5.297 GiB per second  df-passed: 5.297 GiB per second
    total size: 10.731 GiB  df-passed 10.000 GiB
    record DAMON intervals: sample 100 ms, aggr 1 s

As you can see the total df-passed region is 10GiB and the hot region
moves as the seq read keeps going

Revision History
================
Changes from v3 [3]:
- Fix some naming issues and improper text in cover letter raise by SJ.

Changes from v2 [2]:
- Fix some naming and format issues raised by SJ.

Changes from v1 [1]:
- Follow David's advise to combine *pmd_entry() and *pte_entry() into
  one. Also remove manually setting walk->action
- Use vma_normal_page and vma_normal_page_pmd instead of damon_get_folio
  to remove redundant folio_get and folio_put
- Follow SJ's advise to only move damon_pa_scheme_has_filter to
  ops-common
- Change the command used in cover-letter for more natural illustration

[1] https://lore.kernel.org/all/cover.1753794408.git.pyyjason@gmail.com/
[2] https://lore.kernel.org/all/cover.1753895066.git.pyyjason@gmail.com/
[3] https://lore.kernel.org/all/cover.1754088635.git.pyyjason@gmail.com/

Yueyang Pan (2):
  mm/damon/paddr: move filters existence check function to ops-common
  mm/damon/vaddr: support stat-purpose DAMOS filters

 mm/damon/ops-common.c |   9 ++++
 mm/damon/ops-common.h |   2 +
 mm/damon/paddr.c      |  11 +----
 mm/damon/vaddr.c      | 103 +++++++++++++++++++++++++++++++++++++++++-
 4 files changed, 114 insertions(+), 11 deletions(-)

-- 
2.43.0

[PATCH v4 1/2] mm/damon/paddr: move filters existence check function to ops-common

[Yueyang Pan]

This patch moves damon_pa_scheme_has_filter to ops-common. renaming
to damos_ops_has_filter.
Doing so allows us to reuse its logic in the vaddr version
of DAMOS_STAT

Signed-off-by: Yueyang Pan <pyyjason@gmail.com>
---
 mm/damon/ops-common.c |  9 +++++++++
 mm/damon/ops-common.h |  2 ++
 mm/damon/paddr.c      | 11 +----------
 3 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/mm/damon/ops-common.c b/mm/damon/ops-common.c
index 99321ff5cb92..2e3409a6c8a4 100644
--- a/mm/damon/ops-common.c
+++ b/mm/damon/ops-common.c
@@ -412,3 +412,12 @@ unsigned long damon_migrate_pages(struct list_head *folio_list, int target_nid)
 
 	return nr_migrated;
 }
+
+bool damos_ops_has_filter(struct damos *s)
+{
+	struct damos_filter *f;
+
+	damos_for_each_ops_filter(f, s)
+		return true;
+	return false;
+}
diff --git a/mm/damon/ops-common.h b/mm/damon/ops-common.h
index 61ad54aaf256..5efa5b5970de 100644
--- a/mm/damon/ops-common.h
+++ b/mm/damon/ops-common.h
@@ -21,3 +21,5 @@ int damon_hot_score(struct damon_ctx *c, struct damon_region *r,
 
 bool damos_folio_filter_match(struct damos_filter *filter, struct folio *folio);
 unsigned long damon_migrate_pages(struct list_head *folio_list, int target_nid);
+
+bool damos_ops_has_filter(struct damos *s);
diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index 53a55c5114fb..0b67d9321460 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -262,22 +262,13 @@ static unsigned long damon_pa_migrate(struct damon_region *r, struct damos *s,
 	return applied * PAGE_SIZE;
 }
 
-static bool damon_pa_scheme_has_filter(struct damos *s)
-{
-	struct damos_filter *f;
-
-	damos_for_each_ops_filter(f, s)
-		return true;
-	return false;
-}
-
 static unsigned long damon_pa_stat(struct damon_region *r, struct damos *s,
 		unsigned long *sz_filter_passed)
 {
 	unsigned long addr;
 	struct folio *folio;
 
-	if (!damon_pa_scheme_has_filter(s))
+	if (!damos_ops_has_filter(s))
 		return 0;
 
 	addr = r->ar.start;
-- 
2.43.0

[PATCH v4 2/2] mm/damon/vaddr: support stat-purpose DAMOS filters

[Yueyang Pan]

This patch extends DAMOS_STAT handling of the DAMON operations
sets for virtual address spaces for ops-level DAMOS filters.
It leverages the walk_page_range to walk the page table and gets
the folio from page table. The last folio scanned is stored in
damos->last_applied to prevent double counting.

Signed-off-by: Yueyang Pan <pyyjason@gmail.com>
---
 mm/damon/vaddr.c | 103 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 102 insertions(+), 1 deletion(-)

diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
index 87e825349bdf..66ef9869eafe 100644
--- a/mm/damon/vaddr.c
+++ b/mm/damon/vaddr.c
@@ -890,6 +890,107 @@ static unsigned long damos_va_migrate(struct damon_target *target,
 	return applied * PAGE_SIZE;
 }
 
+struct damos_va_stat_private {
+	struct damos *scheme;
+	unsigned long *sz_filter_passed;
+};
+
+static inline bool damos_va_invalid_folio(struct folio *folio,
+		struct damos *s)
+{
+	return !folio || folio == s->last_applied;
+}
+
+static int damos_va_stat_pmd_entry(pmd_t *pmd, unsigned long addr,
+		unsigned long next, struct mm_walk *walk)
+{
+	struct damos_va_stat_private *priv = walk->private;
+	struct damos *s = priv->scheme;
+	unsigned long *sz_filter_passed = priv->sz_filter_passed;
+	struct vm_area_struct *vma = walk->vma;
+	struct folio *folio;
+	spinlock_t *ptl;
+	pte_t *start_pte, *pte, ptent;
+	int nr;
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	if (pmd_trans_huge(*pmd)) {
+		pmd_t pmde;
+
+		ptl = pmd_trans_huge_lock(pmd, vma);
+		if (!ptl)
+			return 0;
+		pmde = pmdp_get(pmd);
+		if (!pmd_present(pmde))
+			goto huge_unlock;
+
+		folio = vm_normal_folio_pmd(vma, addr, pmde);
+
+		if (damos_va_invalid_folio(folio, s))
+			goto huge_unlock;
+
+		if (!damos_va_filter_out(s, folio, vma, addr, NULL, pmd))
+			*sz_filter_passed += folio_size(folio);
+		s->last_applied = folio;
+
+huge_unlock:
+		spin_unlock(ptl);
+		return 0;
+	}
+#endif
+	start_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+	if (!start_pte)
+		return 0;
+
+	for (; addr < next; pte += nr, addr += nr * PAGE_SIZE) {
+		nr = 1;
+		ptent = ptep_get(pte);
+
+		if (pte_none(ptent) || !pte_present(ptent))
+			continue;
+
+		folio = vm_normal_folio(vma, addr, ptent);
+
+		if (damos_va_invalid_folio(folio, s))
+			continue;
+
+		if (!damos_va_filter_out(s, folio, vma, addr, pte, NULL))
+			*sz_filter_passed += folio_size(folio);
+		nr = folio_nr_pages(folio);
+		s->last_applied = folio;
+	}
+	pte_unmap_unlock(start_pte, ptl);
+	return 0;
+}
+
+static unsigned long damos_va_stat(struct damon_target *target,
+		struct damon_region *r, struct damos *s,
+		unsigned long *sz_filter_passed)
+{
+	struct damos_va_stat_private priv;
+	struct mm_struct *mm;
+	struct mm_walk_ops walk_ops = {
+		.pmd_entry = damos_va_stat_pmd_entry,
+		.walk_lock = PGWALK_RDLOCK,
+	};
+
+	priv.scheme = s;
+	priv.sz_filter_passed = sz_filter_passed;
+
+	if (!damos_ops_has_filter(s))
+		return 0;
+
+	mm = damon_get_mm(target);
+	if (!mm)
+		return 0;
+
+	mmap_read_lock(mm);
+	walk_page_range(mm, r->ar.start, r->ar.end, &walk_ops, &priv);
+	mmap_read_unlock(mm);
+	mmput(mm);
+	return 0;
+}
+
 static unsigned long damon_va_apply_scheme(struct damon_ctx *ctx,
 		struct damon_target *t, struct damon_region *r,
 		struct damos *scheme, unsigned long *sz_filter_passed)
@@ -916,7 +1017,7 @@ static unsigned long damon_va_apply_scheme(struct damon_ctx *ctx,
 	case DAMOS_MIGRATE_COLD:
 		return damos_va_migrate(t, r, scheme, sz_filter_passed);
 	case DAMOS_STAT:
-		return 0;
+		return damos_va_stat(t, r, scheme, sz_filter_passed);
 	default:
 		/*
 		 * DAMOS actions that are not yet supported by 'vaddr'.
-- 
2.43.0

Re: [PATCH v4 1/2] mm/damon/paddr: move filters existence check function to ops-common

[SeongJae Park]

On Sat,  2 Aug 2025 11:52:45 +0000 Yueyang Pan <pyyjason@gmail.com> wrote:

> This patch moves damon_pa_scheme_has_filter to ops-common. renaming
> to damos_ops_has_filter.
> Doing so allows us to reuse its logic in the vaddr version
> of DAMOS_STAT
> 
> Signed-off-by: Yueyang Pan <pyyjason@gmail.com>

Reviewed-by: SeongJae Park <sj@kernel.org>


Thanks,
SJ

[...]

Re: [PATCH v4 2/2] mm/damon/vaddr: support stat-purpose DAMOS filters

[SeongJae Park]

On Sat,  2 Aug 2025 11:52:46 +0000 Yueyang Pan <pyyjason@gmail.com> wrote:

> This patch extends DAMOS_STAT handling of the DAMON operations
> sets for virtual address spaces for ops-level DAMOS filters.
> It leverages the walk_page_range to walk the page table and gets
> the folio from page table. The last folio scanned is stored in
> damos->last_applied to prevent double counting.
> 
> Signed-off-by: Yueyang Pan <pyyjason@gmail.com>

Reviewed-by: SeongJae Park <sj@kernel.org>


Thanks,
SJ

[...]

Re: [PATCH v4 0/2] mm/damon/vaddr: support stat-purpose DAMOS filters

[SeongJae Park]

On Sat,  2 Aug 2025 11:52:44 +0000 Yueyang Pan <pyyjason@gmail.com> wrote:

> Extend DAMOS_STAT handling of the DAMON operations sets for virtual
> address spaces for ops-level DAMOS filters.
> 
> Functionality Test
> ==================
> I wrote a small test program which allocates 10GB of DRAM, use 
> madvise(MADV_HUGEPAGE) to convert the base pages to 2MB huge pages
> Then my program does the following things in order:
> 1. Write sequentially to the whole 10GB region
> 2. Read the first 5GB region sequentially for 10 times
> 3. Sleep 5s
> 4. Read the second 5GB region sequentially for 10 times
> 
> With a proper damon setting, we are expected to see df-passed to be 10GB
> and hot region move around with the read
> 
> $ # Start DAMON
> $ sudo ./damo/damo start "./my_test/test" --monitoring_intervals 100ms\
> 1s 2s

On v2, I also suggested adding indentation here, same to the outputs of the
commands.  But, this is too trivial, so I wouldn't request a new version.

[...]
> Revision History
> ================
> Changes from v3 [3]:
> - Fix some naming issues and improper text in cover letter raise by SJ.

All looks good to me, I gave my Reviewed-by: tags to all patches.  Thank you
for doing this great work, Pan!


Thanks,
SJ

[...]