linux-kernel - Re: [PATCH v1 01/31] x86/resctrl: Fix allocation of cleanest CLOSID on platforms with no monitors

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Date: Fri, 12 Apr 2024 17:17:58 +0100
From: Dave Martin <Dave.Martin@....com>
To: Reinette Chatre <reinette.chatre@...el.com>
Cc: David Hildenbrand <david@...hat.com>, James Morse <james.morse@....com>,
	x86@...nel.org, linux-kernel@...r.kernel.org,
	Fenghua Yu <fenghua.yu@...el.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	H Peter Anvin <hpa@...or.com>, Babu Moger <Babu.Moger@....com>,
	shameerali.kolothum.thodi@...wei.com,
	D Scott Phillips OS <scott@...amperecomputing.com>,
	carl@...amperecomputing.com, lcherian@...vell.com,
	bobo.shaobowang@...wei.com, tan.shaopeng@...itsu.com,
	baolin.wang@...ux.alibaba.com, Jamie Iles <quic_jiles@...cinc.com>,
	Xin Hao <xhao@...ux.alibaba.com>, peternewman@...gle.com,
	dfustini@...libre.com, amitsinght@...vell.com,
	Rex Nie <rex.nie@...uarmicro.com>
Subject: Re: [PATCH v1 01/31] x86/resctrl: Fix allocation of cleanest CLOSID
 on platforms with no monitors

On Thu, Apr 11, 2024 at 10:35:56AM -0700, Reinette Chatre wrote:
> Hi Dave,
> 
> On 4/11/2024 7:13 AM, Dave Martin wrote:
> > On Tue, Apr 09, 2024 at 10:05:33AM +0200, David Hildenbrand wrote:
> >> On 21.03.24 17:50, James Morse wrote:
> >>> commit 6eac36bb9eb0 ("x86/resctrl: Allocate the cleanest CLOSID by
> >>> searching closid_num_dirty_rmid") added a Kconfig option that causes
> >>> resctrl to search for the CLOSID with the fewest dirty cache lines when
> >>> creating a new control group. This depends on the values read from the
> >>> llc_occupancy counters.
> > 
> > [...]
> > 
> >> It's weird to not see RESCTRL_RMID_DEPENDS_ON_CLOSID appear in any Kconfig file.
> >> I guess it will all make sense once the refactoring is done :)
> > 
> > Agreed; a stub Kconfig item could be added, but since the file layout
> > and naming conventions change after this patch, doing this would
> > probably just create noise in the series though.
> > 
> > Looking at <linux/kconfig.h> (yikes!), IS_ENABLED() is designed to do
> > the right thing for non-existing Kconfigs...
> > 
> > If nobody is too concerned about the temporarily dangling IS_ENABLED()s
> > in this series, I won't propose any change here.
> 
> I am not concerned about this. Please note that these IS_ENABLED() checks
> are not introduced in this series, they were introduced in the previous
> portion of this MPAM work that can be found in upstream resctrl.
> 
> Reinette
> 

Ah, right.  Thanks for the explanation.

Cheers
---Dave