On 7/16/2025 11:51 AM, SeongJae Park wrote:
On Wed, 16 Jul 2025 10:58:06 +0900 Honggyu Kim <honggyu.kim@xxxxxx> wrote:
Hi SeongJae,
On 7/16/2025 8:43 AM, SeongJae Park wrote:
On Wed, 16 Jul 2025 07:20:57 +0900 Honggyu Kim <honggyu.kim@xxxxxx> wrote:
Hi SeongJae,
On 7/13/2025 5:46 AM, SeongJae Park wrote:
DAMON sysfs interface provides files for reading DAMON internal status
including DAMOS stats. The content of the files are not automatically
updated, though. Users should manually request updates of the contents
by writing a special command to 'state' file of each kdamond directory.
This interface is good for minimizing overhead, but causes the below
problems.
[...snip...]
Introduce a new sysfs file, namely refresh_ms, for asking DAMON sysfs
interface to repeat the essential contents update with a user-specified
time delay.
Thanks for working on this, but I have a few questions.
1. Could you please list up what are the "essential contents"?
Thank you for asking this. The contents are auto-tuned monitoring intervals,
DAMOS stats, and auto-tuned effective size quota.
Thanks, but I meant the specific list of damon knobs refreshed. If there are
too many knobs, then don't have to list them all.
I guess you are saying about sysfs files? Yes, I think listing those all is
unnecessary.
OK. No problem then.
I will add these on the next version cover letter.
Thanks.
2. Does it mean that it is different from writing "commit" to "state"?
3. If not, then is there equivalent action to writing something to "state"?
"refresh_ms" works same to other DAMON parameter files. You can set it before
starting DAMON, or "commit" new values (including 0 for turning this refresh
off) in runtime.
I'm not that confident if I understood your point very well, especially what
"it"s mean. Let me know if I'm misunderstanding something.
I mean writing "commit" to "state" refresh all knobs,
Assuming "knobs" mean sysfs files, this is incorrect. Writing "commit" to
"state" passes the parameters written on appropriate files to running kdamond.
It doesn't update any sysfs files until a "update_*" keyword is written to the
"state" file.
I thought writing "commit" to "state" applies config changes and updates all the
readable sysfs files together, but it doesn't. Thanks for the correction.
but it seems "refresh_ms"
internally refresh paritial knobs so I was wondering what are refreshed and what
aren't.
Regarding the "equivalent action", I was also wondering if there is a command
that works same as "refresh_ms" internally does among the command below.
update_tuned_intervals
commit_schemes_quota_goals
update_schemes_stats
update_schemes_tried_regions
update_schemes_tried_bytes
clear_schemes_tried_regions
update_schemes_effective_quotas
https://docs.kernel.org/admin-guide/mm/damon/usage.html#kdamonds-n
In other words, if there is the same command listed above, then users might be
able to run a script that regularaly write the command to the current "state"
even without this "refresh_ms". I know having "refresh_ms" is much better
though.
Thank you for this nice question. Yes. Enabling "refresh_ms" is roughly same
to periodically writing
"update_{tuned_intervals,schemes_stats,schemes_effective_quotas" to "state"
file.
OK. I get that "refresh_ms" does periodic write the combination of them to
"state" without "update_{schemes_tried_regions,schemes_tried_bytes}.
In other words, it is same as periodic execution of the follows.
echo update_tuned_intervals > state
echo update_schemes_stats > state
echo update_schemes_effective_quotas > state
That makes my question clear. Thanks for the explanation!
Thanks,
Honggyu
Thanks,
SJ
[...]
