Re: [PATCH 0/1] coresched: Manage core scheduling cookies for tasks

[Phil Auld <pauld@redhat.com>]

On Tue, Mar 26, 2024 at 08:26:23PM +0100 Thijs Raymakers wrote:
> Op 26-03-2024 om 20:09 schreef Phil Auld:
> > I tried this version out and it doesn't work for me. One of the
> > basic use cases of a wrapper like this is to run a command with
> > a new cookie (say starting a container or something).
> > 
> > Coresched requires a pid to do that:
> >  # ./coresched -n ls
> >  coresched: Failed to parse PID for -n/--new: 'ls'   
> > 
> > With my coreset utility it does work and gives some information about what
> > it did:
> > 
> >  # coreset -n ls
> >  pid 20860's current cookie: 0x0
> >  pid 20860's new cookie: 0xa9fcfbf1
> >  ABOUT-NLS        chrt           configure      ionice        libsmartcols  Makefile.in
> > ...
> > 
> > Did I miss something?  I think this will be one of the primary use cases for
> > this utility.
> 
> Hi Phil,
> 
> The following command works
> 
> # ./coresched ls
> chrt.1	    chrt.1.deps  coresched.1.adoc  coresched.o  ionice.1.adoc
> ...

Hhm, I'd prefer the no argument case to be a noop. 

But okay, I was missing something :)  This is where some output might
have helped though ...

So "-n/--new" creates a new cookie and so does "". Just one on an existing task
and one on the exec'd task.  Seems inconsistent, no?

> 
> By default, it will spawn the provided program with a new core
> scheduling cookie.
>

See above about default. But maybe that's just my taste.

Since you have expplicit commands to do things why not just make --get be
the default no command one?  So coresched -p 1234  just reports the cookie
of pid 1234 or corsched ls just reports (in this case the meaningless) cookie
of the exec'd ls command.

The use the -n and friends as an action operation to create/copy etc.


> This command
> # ./coresched -n 123
> 
> is to assign a new core scheduling cookie to PID 123. The commands don't
> show what the current and/or new cookie is, because that is of limited
> utility in my opinion (and --get also does this).

Yes, true. But it's sometimes nice to see that the command you ran did
something,


But anyway, that's more of my 2 cents. I'll try it again with new
knowledge.


Cheers,
Phil



> You can only use it to check if two programs have the same cookie.
> An error message will be printed and the exit code will be set if it
> doesn't succeed. Otherwise,
> if the program succeeds then it won't write anything to stderr/stdout.
> 
> Thijs
> 

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