Re: [PATCH v3 5/5] alloc_tag: config to store page allocation tag refs in page flags

Michal Hocko
2024-10-21T15:34:33Z

On Mon 21-10-24 08:05:16, Suren Baghdasaryan wrote:
[...]
> Yeah, I thought about adding new values to "mem_profiling" but it's a
> bit complicated. Today it's a tristate:
>
> mem_profiling=0|1|never
>
> 0/1 means we disable/enable memory profiling by default but the user
> can enable it at runtime using a sysctl. This means that we enable
> page_ext at boot even when it's set to 0.
> "never" means we do not enable page_ext, memory profiling is disabled
> and sysctl to enable it will not be exposed. Used when a distribution
> has CONFIG_MEM_ALLOC_PROFILING=y but the user does not use it and does
> not want to waste memory on enabling page_ext.
>
> I can add another option like "pgflags" but then it also needs to
> specify whether we should enable or disable profiling by default
> (similar to 0|1 for page_ext mode). IOW we will need to encode also
> the default state we want. Something like this:
>
> mem_profiling=0|1|never|pgflags_on|pgflags_off
>
> Would this be acceptable?

Isn't this overcomplicating it? Why cannot you simply go with
mem_profiling={0|never|1}[,$YOUR_OPTIONS]

While $YOUR_OPTIONS could be compress,fallback,ponies and it would apply
or just be ignored if that is not applicable.
--
Michal Hocko
SUSE Labs