Re: [RFC PATCH 0/2] DAMON: add priority-based scheme application control

[SeongJae Park <sj@kernel.org>]

Hello Enze,

On Mon, 22 Sep 2025 18:10:20 +0800 Enze Li <lienze@kylinos.cn> wrote:

> This patchset introduces a priority mechanism for DAMON's scheme
> application, allowing users to specify the relative importance of
> monitored processes.  The changes ensure that higher-priority targets
> receive more frequent memory management operations while maintaining
> fairness across all monitored processes.

Thank you for this patchset.

There are features for monitoring target-based DAMOS filtering
(DAMOS_FILTER_TYPE_TARGET) and per-scheme applying time interval
(apply_interval_us).  Couldn't those be used for your purpose?

> 
> The first patch modifies kdamond_apply_schemes to implement
> priority-based scheduling, where targets are processed in proportion to
> their assigned priority values.  For example, a target with priority 50
> will be serviced 50 times for every 30 times a target with priority 30
> is processed.
> 
> The second patch adds a sysfs interface (priority under each target's
> directory) to dynamically configure these priorities at runtime. This
> enables fine-grained control over DAMON's behavior, making it more
> adaptable to performance-sensitive workloads.
> 
> Together, these changes provide better flexibility for users who need
> differentiated memory management policies across different processes
> while maintaining backward compatibility with existing setups.
> 
> You may want to verify this feature using the following testing
> procedure:
> 
>  # git clone -b v2 https://github.com/lienze/damo.git
>  # cd damo
>  # ./damo start --target_pid $(pidof <target1>) --priority 50 \
>  --target_pid $(pidof <target2>) --priority 30 --damos_action \
>  pageout --damos_age 5s 5s

So I'm wondering a command like below could be used instead.

$ sudo ./damo args damon \
	--target_pid 123 \
		--damos_action pageout --damos_age 5s 5s \
		--damos_filter allow target 0 --damos_apply_interval 3s \
	--target_pid 456 \
		--damos_action pageout --damos_age 5s 5s \
		--damos_filter allow target 1 --damos_apply_interval 5s \
	--damos_nr_filters 1 1


Thanks,
SJ

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