Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <20191120081628.26701-1-yu.c.chen@intel.com> <alpine.DEB.2.21.1911201055260.6731@nanos.tec.linutronix.de>
In-Reply-To: <alpine.DEB.2.21.1911201055260.6731@nanos.tec.linutronix.de>
From:   Yu Chen <yu.chen.surf@gmail.com>
Date:   Fri, 22 Nov 2019 16:18:46 +0800
Message-ID: <CADjb_WR4Lwjdu9aQOnfm21rcYqoAK-25V-cmRABPzpduUWBGsQ@mail.gmail.com>
Subject: Re: [PATCH][v3] x86/resctrl: Add task resctrl information display
To:     Thomas Gleixner <tglx@linutronix.de>
Cc:     Chen Yu <yu.c.chen@intel.com>,
        "the arch/x86 maintainers" <x86@kernel.org>,
        Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
        Fenghua Yu <fenghua.yu@intel.com>,
        Reinette Chatre <reinette.chatre@intel.com>,
        Tony Luck <tony.luck@intel.com>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
        Michal Hocko <mhocko@suse.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-fsdevel@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Thomas,
On Wed, Nov 20, 2019 at 7:23 PM Thomas Gleixner <tglx@linutronix.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