linux-kernel - Re: [PATCH][v3] x86/resctrl: Add task resctrl information display

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Date:   Fri, 22 Nov 2019 16:18:46 +0800
From:   Yu Chen <yu.chen.surf@...il.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Chen Yu <yu.c.chen@...el.com>,
        "the arch/x86 maintainers" <x86@...nel.org>,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Michal Hocko <mhocko@...e.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-fsdevel@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH][v3] x86/resctrl: Add task resctrl information display

Hi Thomas,
On Wed, Nov 20, 2019 at 7:23 PM Thomas Gleixner <tglx@...utronix.de> wrote:
>
> On Wed, 20 Nov 2019, Chen Yu wrote:
> > Monitoring tools that want to find out which resctrl CTRL
> > and MONITOR groups a task belongs to must currently read
> > the "tasks" file in every group until they locate the process
> > ID.
> >
> > Add an additional file /proc/{pid}/resctrl to provide this
> > information.
> >
> > For example:
> >  cat /proc/1193/resctrl
> > CTRL_MON:/ctrl_grp0
> > MON:/ctrl_grp0/mon_groups/mon_grp0
>
> The formatting is quite ugly and I don't see why this needs to be multiple
> lines and have these uppercase prefixes.
>
> A task can only be part of one control group and of one monitoring group
> which is associated to the control group. So just providing:
>
>  1)   ""
>  2)   "/"
>  3)   "/mon_groups/mon0"
>  4)   "/group0"
>  5)   "/group0/mon_groups/mon1"
>
> is simple and clear enough, i.e.:
>
> #1: Resctrl is not available
>
> #2: Task is part of the root group, task not associated to any monitoring
>     group
>
> #3: Task is part of the root group and monitoring group mon0
>
> #4: Task is part of control group group0, task not associated to any
>     monitoring group
>
> #5: Task is part of control group group0 and monitoring group mon1
>
> Hmm?
>
Yes, good idea, this is much more simpler.  I'll send the new version
out based on this.

Thanks,
Chenyu