Re: [PATCH REPOST 0/5] mm/damon/vaddr: support {prep,apply}_probes

[Gutierrez Asier]

Hi SJ,

On 9/9/2026 5:04 PM, SJ Park wrote:
> DAMON supports data attributes monitoring.  However, only the physical
> address space operation set (paddr) is supporting it.  Add the support
> to the virtual address space operation set (vaddr).
> 
> Patch 1 adds prep_probes support to vaddr.  Patch 2 moves probe filter
> handling code in paddr.c that can be reused by vaddr to ops-common.c.
> Patch 3 adds minimum apply_probes support to vaddr.  Patch 4 extends the
> support for hugetlb.  Patch 5 extends the support for pgidle_unset
> filter.
> 
> Test
> ====
> 
> I confirmed it can capture ~48 mb working set of masim in vaddr mode,
> like below.
> 
> First, start masim [1] to access ~48 mb memory at a time, in the
> background.
> 
>     $ ./masim/masim.py run \
>             --config_file ./masim/configs/stairs-50mb.cfg \
>             --repeat 10 --quiet &
> 
> Note that the config says the working set is 50mb.  It is 50 million
> bytes, so ~48 MiB.
> 
> Start traditional access monitoring of masim's virtual address space
> using damo [2].
> 
>     $ sudo ./damo/damo start $(pidof masim)
> 
> Confirm it can capture the ~48 MiB working set as the 4-th region on the
> snapshot.
> 
>     $ sudo ./damo/damo report access
>     heatmap:
>     11111111334[...]3000000000000000000000000000000000000000489999997777777743333333555556[...]8
>     # min/max temperatures: -1,150,000,000, 80,009,499, column size: 6.963
>     MiB
>     intervals: sample 5 ms aggr 100 ms (max access hz 200)
>     0   addr 85.355 TiB   size 55.703 MiB  access 0 hz   age 9.500 s
>     1   addr 85.355 TiB   size 18.984 MiB  access 0 hz   age 6.700 s
>     2   addr 127.183 TiB  size 278.516 MiB access 0 hz   age 11.500 s
>     3   addr 127.183 TiB  size 7.570 MiB   access 0 hz   age 900 ms
>     4   addr 127.183 TiB  size 48.133 MiB  access 190 hz age 800 ms
>     5   addr 127.183 TiB  size 54.977 MiB  access 0 hz   age 1.700 s
>     6   addr 127.183 TiB  size 55.113 MiB  access 0 hz   age 6.700 s
>     7   addr 127.183 TiB  size 37.902 MiB  access 0 hz   age 3.900 s
>     8   addr 127.990 TiB  size 120.000 KiB access 0 hz   age 11.400 s
>     9   addr 127.990 TiB  size 8.000 KiB   access 70 hz  age 0 ns
>     10  addr 127.990 TiB  size 4.000 KiB   access 0 hz   age 11.200 s
>     memory bw estimate: 8.931 GiB per second
>     total size: 557.027 MiB
>     record DAMON intervals: sample 5 ms, aggr 100 ms
> 
> Stop access monitoring and start probe-only mode access monitoring.
> 
>     $ sudo ./damo/damo stop
>     $ sudo ./damo/damo start $(pidof masim) --probe_prep set_pgidle \
>             --probe_filter allow pgidle_unset --probe_weight 1
> 
> Confirm it can also capture the ~48 MiB working set as the 11-th region
> on the snapshot.
> 
>     $ sudo ./damo/damo report attrs
>     heatmap:
>     00000000113[...]40000000000000000000000000000000000000000000000001111114999999533333336[...]6
>     # min/max temperatures: -840,000,000, 330,002,000, column size: 6.961
>     MiB
>     probe prep: set_pgidle, filter: allow pgidle_unset (weight: 1)
>     intervals: sample 5 ms aggr 100 ms (max probe hits 20)
>     #   size         address       age           probe_hits
>     0   8.000 KiB    127.990 TiB   8.700 s       0
>     1   120.000 KiB  127.990 TiB   8.600 s       0
>     2   55.543 MiB   127.183 TiB   8.400 s       0
>     3   110.008 MiB  127.183 TiB   8.300 s       0
>     4   55.352 MiB   127.183 TiB   8.100 s       0
>     5   55.605 MiB   127.183 TiB   8 s           0
>     6   55.691 MiB   85.355 TiB    7.900 s       0
>     7   54.430 MiB   127.183 TiB   7.900 s       0
>     8   50.391 MiB   127.183 TiB   6.900 s       0
>     9   18.879 MiB   85.355 TiB    6 s           0
>     10  52.844 MiB   127.183 TiB   3.500 s       0
>     11  48.039 MiB   127.183 TiB   3.300 s       20
>     12  4.000 KiB    127.990 TiB   8.500 s       20
>     memory bw estimate: 0 B per second
>     total size: 556.910 MiB
>     record DAMON intervals: sample 5 ms, aggr 100 ms
> 
> [1] https://github.com/sjp38/masim
> [2] https://github.com/damonitor/damo
> 
> Changes from v1 original post
> - v1: https://lore.kernel.org/20260906184417.96621-1-sj@xxxxxxxxxx
> - Rebase to latest mm-new.
> Changes from RFC
> - RFC: https://lore.kernel.org/20260905202634.88102-1-sj@xxxxxxxxxx
> - Drop RFC tag.
> - Rebase to latest mm-new.
> 
> SJ Park (5):
>   mm/damon/vaddr: support prep_probes
>   mm/damon/paddr: move probe filter handling to ops-common
>   mm/damon/vaddr: support apply_probe
>   mm/damon/vaddr: extend apply_probes() for hugetlb
>   mm/damon/vaddr: support pgidle_unset probe filter type
> 
>  mm/damon/ops-common.c |  32 ++++++
>  mm/damon/ops-common.h |   2 +
>  mm/damon/paddr.c      |  23 +----
>  mm/damon/vaddr.c      | 232 ++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 267 insertions(+), 22 deletions(-)
> 
> 
> base-commit: da659d141e9797b3a2e5d0e2b457bfa4e8a8cb2d

Nice to see the progress with probes.

Since you are adding prep_probes for vaddr, do we need to check for
the existence of prep_probes in kdamond_fn?

How about this?

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 645cb367019a..7b308cbf21ab 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -3935,7 +3935,7 @@ static int kdamond_fn(void *data)
                if (kdamond_wait_activation(ctx))
                        break;
 
-               do_prep = ctx->ops.prep_probes && damon_has_prep(ctx);
+               do_prep = damon_has_prep(ctx);
 
                if (!access_check_disabled && ctx->ops.prepare_access_checks)
                        ctx->ops.prepare_access_checks(ctx);

And maybe change the name of the variable to has_prep.

-- 
Asier Gutierrez
Huawei