On Sun 22-08-21 17:46:08, yong w wrote:

quoted

All those reasons should be a part of the changelog.
....
I am not sure these are sufficient justifications but that is something
to discuss. And hence it should be a part of the changelog.

OK, These reasons will be added to the patch notesin later versions.

quoted

quoted

3. In the case where the user does not need vmpressure,  vmpressure
calculation is additional overhead.

You should quantify that and argue why that overhead cannot be further
reduced without config/boot time knobs.

The test results of the previously used PFT tool may not be obvious.
Is there a better way to quantify it?

This is a question for you to answer I am afraid. You want to add a
configuration option and (as explained) that is not free of cost from
the maintenance POV. There must a very good reason to do that.

quoted

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In some special scenes with tight memory, vmpressure will be executed
frequently.we use "likely" and "inline"
to improve the performance of the kernel, why not reduce some
unnecessary calculations?

I am all for improving the code. Is it possible to do it by other means?
E.g. reduce a potential overhead when there no events registered?

Yes, the method you mentioned may be feasible, but it does not conflict
with this patch.

It is not in conflict but runtime overhead reduction without more burden
on the configurability is usually a preferred approach.
-- 
Michal Hocko
SUSE Labs