Simple system stats.

[Andre Schmidt]

On Sat, 2 Nov 2019 14:13:08 +0100
Greg KH <greg at kroah.com> wrote:

> On Sat, Nov 02, 2019 at 02:05:19PM +0100, Andre Schmidt wrote:
> > On Sat, 2 Nov 2019 13:07:00 +0100
> > Greg KH <greg at kroah.com> wrote:
> > 
> > > On Sat, Nov 02, 2019 at 12:51:05PM +0100, Andre Schmidt wrote:
> > > > Hello kernel space,
> > > > 
> > > > user space webmonkey here, tinkering on my home desktop setup and spelunking way too many rabbit holes... damn you source code! ;P
> > > > 
> > > > The other day i got frustrated with re-implementing parsing and calculation of /proc/stat and /proc/meminfo for my visual user interface experiments (in various languages), so i "created"* a kernel module that helps me with that (https://github.com/oskude/proc_topstat).
> > > > 
> > > > But i could not get swap info in the kernel module, cause - i guess - it's not exported?
> > > > So i wonder, would/could upstream EXPORT_SYMBOL(si_swapinfo)?
> > > > If yes/maybe, where/how should i propose such change?
> > >
> > > Symbols and functions are only exported if an in-kernel-tree module
> > > needs it.  Sorry.
> > >
> > > What's wrong with parsing the existing exports of this value as-is?
> > 
> > do you mean i can get swap usage info in a kernel module without si_swapinfo?
> 
> Not that I know of, no.
> 
> > (as seen here https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/fs/proc/meminfo.c#n44)
> > 
> > or do you mean what is wrong with /proc/meminfo?
> 
> Yes, what is wrong with that?

I guess there's nothing "wrong" with /proc/meminfo (or /proc/stat), i just want to display their - for me/user relevant - data every 250ms and parsing them felt so sub-optimal... So i just removed what i didn't need and pre-calculated what i could, in the kernel module. So i would not need to worry about it again (except, yeah, when upstream changes).

Also, as i dabble in various programming languages (in userspace), i would need to re-implement the parsing and calculation (that matters to me/user) of /proc/stat and /proc/meminfo every time...
(but i guess that is userspace work? translate kernelspace data to userspace data? does "user" even mean "human"?;P)

But whatever, i now like this more:

$> cat /proc/topstat 
cpu 2085949 109734
cpu 2086513 108671
cpu 2086203 110817
cpu 2086167 127600
mem 8026148 2993832 1033648

cpu <total> <used>
- line number implies cpu number.
- <total> jiffies elapsed.
- <used> amount of <total> in use by programs, that cannot be used by other programs.

mem <total> <used> <cached>
- <total> kilobytes of memory.
- <used> amount of <total> in use by programs, that can not be used by other programs.
- <cached> amount of <used> in use for caches, that can be freed by user.

For now, i can live without swap ui, i avoid swap anyway :D

Cheers
Andre Schmidt