Re: [RFC] mm/damon/damo: saving damon sysfs configuration

[Liew Rui Yan <aethernet65535@gmail.com>]

On Thu, 08 Oct 2026 08:00:43 -0700 SJ Park <sj@kernel.org> wrote:

> On Thu,  8 Oct 2026 21:44:19 +0800 Liew Rui Yan <aethernet65535@gmail.com> wrote:
> 
> > On Thu, 08 Oct 2026 05:32:31 -0700 SJ Park <sj@kernel.org> wrote:
> > 
> > > Hi Liew,
> > > 
> > > On Thu,  8 Oct 2026 20:09:05 +0800 Liew Rui Yan <aethernet65535@gmail.com> wrote:
> > > 
> > > > Hi SJ,
> > > > 
> > > > Just a reminder, I think you might have missed the question I asked.
> > > 
> > > Could you please clarify what is the question that is not yet answered?
> > 
> > It seems I forgot to ask the question, my apologies.
> 
> No worry!
> 
> > 
> > I would like to ask: after reviewing the reproduction, do you still
> > think this is a real issue?  If so, I will start working on a fix.
> 
> I'm not good at reading the diff in your previous reply.  It makes me difficult
> to understand what the issue is.  So I tried the commands on my system.
> 
> '''
> $ sudo ./damo start
> $ sudo ./damo args damon > damo_args_damon.json
> $ sudo ./damo report damon --json > damo_report_damon.json
> $ sudo ./damo stop
> $ sudo ./damo start --kdamonds damo_args_damon.json
> $ sudo ./damo report damon --json > damo_report_damon_aftr.json
> $ diff -u damo_report_damon.json damo_report_damon_aftr.json
> --- damo_report_damon.json      2026-10-08 07:56:04.979178016 -0700
> +++ damo_report_damon_aftr.json 2026-10-08 07:56:27.717941609 -0700
> @@ -1,7 +1,7 @@
>  [
>      {
>          "state": "on",
> -        "pid": "46402",
> +        "pid": "46449",
>          "refresh_ms": 0,
>          "contexts": [
>              {
> '''
> 
> And still it is unclear what is the problem.  Could I ask your elaboration?

Thank you for testing this!

The reason it did not reproduce is that no DAMOS Schemes were configured
during this test.

This is a bash script for reproduce:

'''
#!/bin/bash

mkdir -p /tmp/config
mkdir -p /tmp/output

./damo args damon \
--kdamond --damon_ctx --ops paddr \
    --monitoring_intervals 5000 100000 1000000 \
    --damon_target --regions 0-4096 \
    --damos_scheme --damos_action lru_deprio \
        --damos_sz_region 4096 max \
        --damos_access_rate 0 max \
        --damos_age 120000000 max \
        --damos_quota_interval 1000 \
        --damos_quota_time 0 \
        --damos_quota_space 16777216 \
        --damos_quota_weights 0 1000 1000 \
> /tmp/config/lru.json

./damo stop
./damo start --kdamonds /tmp/config/lru.json
./damo args damon > /tmp/output/damo_args_damon.json
./damo report damon --json > /tmp/output/damo_report_damon.json
./damo stop
./damo start --kdamonds /tmp/output/damo_args_damon.json
./damo report damon --json > /tmp/output/damo_report_damon_aftr.json
diff -u /tmp/output/damo_report_damon.json /tmp/output/damo_report_damon_aftr.json
./damo stop

rm -r /tmp/config
rm -r /tmp/output
'''

[...]

Best regards,
Rui Yan