Re: free: regression due to a different calculation of Used memory

On Thu 29-04-21 14:30:36, Michal Hocko wrote:
> On Thu 29-04-21 22:08:31, Craig Small wrote:
[...]
> > proc(5) says Cached (as in the line /proc/meminfo ) is only based on disk,
> > or in its words
> >   "In-memory cache for files read from the disk (the page cache).  Doesn't
> > include SwapCached."
> > 
> > Is the man page incorrect?
> 
> yes and no. It is correct in the sense that swapcache is explicitly
> excluded but it is not fully correct claiming it is disk backed file
> cache. Because it includes shmem which is a filesystem which is not
> backed by disk (except for the swapout).
> 
> A proper wording would be: In-memory cache for filesystem content (both
> disk based as memory based like shmem). Doesn't include Swap cache and
> buffer cache which are presented separately (SwapCached resp. Buffers).

Should I send a patch to clarify this?

> > I think that's the main difference now.  Ideally this could be settled by
> > the kernel exposing MemUsed in /proc/meminfo and everyone can use that
> > (it's how available was solved).
> 
> Why Total-Available doesn't serve that purpose already?

Would be a patch to change the behavior to use Total-Available at least
considered?
-- 
Michal Hocko
SUSE Labs