linux-kernel - Re: [PATCH V16 00/11] x86: Intel Cache Allocation Technology Support

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Message-ID: <alpine.DEB.2.20.1512210649350.7119@east.gentwo.org>
Date:	Mon, 21 Dec 2015 06:53:20 -0600 (CST)
From:	Christoph Lameter <cl@...ux.com>
To:	Marcelo Tosatti <mtosatti@...hat.com>
cc:	Fenghua Yu <fenghua.yu@...el.com>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Tony Luck <tony.luck@...el.com>,
	Ravi V Shankar <ravi.v.shankar@...el.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Tejun Heo <tj@...nel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>, x86 <x86@...nel.org>
Subject: Re: [PATCH V16 00/11] x86: Intel Cache Allocation Technology
 Support

On Fri, 18 Dec 2015, Marcelo Tosatti wrote:

> > Could you also support another low level interface where a task (or
> > process) can set the CLOS id itself if it has CAP_SYS_NICE.
>
> Hi Christoph,
>
> Do you have a proposal for an interface?

Syscall set_closid(int closid) for an app. The CLOS id should be
listed in /proc/<pid>/status

And then /proc/clos listing the possible configs with their current
setups.

Or /proc/clos/<closid>/<value>. Then have the ability to modify
those for the root user.

> >  Plus some way
> > for the supervisor to directly control the IA32_L3_MASK_n MSR?
>
> What you mean supervisor? Hypervisor or root user?

Root user.
>
> > Is there a way to see these values for debugging purposes?
>
> Yes, from userspace, wrmsr and rdmsr.

Maybe have a nicer way to interact with these configurations via /proc?
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