linux-kernel - Re: [PATCH v21 14/18] x86/resctrl: Fill out rmid_read structure for smp

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Message-ID: <7f6080b8-daf7-4666-9a9b-8ebc8d7ac504@intel.com>
Date: Thu, 27 Jun 2024 10:52:18 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: "Luck, Tony" <tony.luck@...el.com>
CC: "Yu, Fenghua" <fenghua.yu@...el.com>, "Wieczor-Retman, Maciej"
	<maciej.wieczor-retman@...el.com>, Peter Newman <peternewman@...gle.com>,
	James Morse <james.morse@....com>, Babu Moger <babu.moger@....com>, "Drew
 Fustini" <dfustini@...libre.com>, Dave Martin <Dave.Martin@....com>,
	"x86@...nel.org" <x86@...nel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "patches@...ts.linux.dev"
	<patches@...ts.linux.dev>
Subject: Re: [PATCH v21 14/18] x86/resctrl: Fill out rmid_read structure for
 smp_call*() to read a counter

Hi Tony,

On 6/27/24 10:31 AM, Luck, Tony wrote:
>>> Or do they serve as useful hints to human readers of the code?
>>
>> You are of course welcome to keep those you find useful to readers of the
>> code. My goals with this suggestion was to (a) stop passing garbage in
>> struct rmid_read fields, (b) use struct rmid_read consistently.
> 
> Reinette,
> 
> I dug through the code and found only two existing redundant assignments:
> 
> 	rr->val = 0; (in mon_event_read())
> and:
> 	rr.first = false; (in mbm_update())
> 
> plus a third added by my patch 14:
> 	rr.ci = NULL; (in mbm_update())
> 
> None of them seem particularly helpful hints, so I'm dropping
> all three in the next rev. of the series.

Sounds good.

I think there is one more redundant assignment in mbm_update():
	if (is_mbm_total_enabled()) {
		...
		rr.val = 0;
		...
	}

... but I think it may be subtle enough to keep to be consistent with
the rr.val = 0 in the following if() block that _is_ needed.

Reinette