linux-kernel - Re: [PATCH v20 09/18] x86/resctrl: Add a new field to struct rmid

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Date: Thu, 20 Jun 2024 14:22:43 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Tony Luck <tony.luck@...el.com>, Fenghua Yu <fenghua.yu@...el.com>,
	"Maciej Wieczor-Retman" <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>
CC: <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
	<patches@...ts.linux.dev>
Subject: Re: [PATCH v20 09/18] x86/resctrl: Add a new field to struct
 rmid_read for summation of domains

Hi Tony,

On 6/10/24 11:35 AM, Tony Luck wrote:
> When a user reads a monitor file rdtgroup_mondata_show() calls
> mon_event_read() to package up all the required details into an rmid_read
> structure which is passed across the smp_call*() infrastructure to code
> that will read data from hardware and return the value (or error status)
> in the rmid_read structure.
> 
> Sub-NUMA Cluster (SNC) mode adds files with new semantics. These require
> the smp_call-ed code to sum event data from all domains that share an
> L3 cache.
> 
> Add a pointer to the L3 "cacheinfo" structure to struct rmid_read
> for the data collection routines to use to pick the domains to be
> summed.
> 
> Reinette suggested that the rmid_read structure has become complex
> enough to warrant documentation of each of its fields. Add the kerneldoc
> documentation for struct rmid_read.
> 
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---
>   arch/x86/kernel/cpu/resctrl/internal.h | 13 +++++++++++++
>   1 file changed, 13 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 99f601d05f3b..d29c7b58c151 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -145,12 +145,25 @@ union mon_data_bits {
>   	} u;
>   };
>   
> +/**
> + * struct rmid_read - Data passed across smp_call*() to read event count
> + * @rgrp:	Resctrl group
> + * @r:		Resource
> + * @d:		Domain. If NULL then sum all domains in @r sharing L3 @ci.id
> + * @evtid:	Which monitor event to read
> + * @first:	Initializes MBM counter when true
> + * @ci:		Cacheinfo for L3. Used when summing domains
> + * @err:	Return error indication
> + * @val:	Return value of event counter
> + * @arch_mon_ctx: Hardware monitor allocated for this read request (MPAM only)
> + */

Thank you for adding the kerneldoc. I understand that this file is not
consistent on how these kerneldoc are formatted, but could you please
pick whether you think sentences need to end with a period and then stick
to it in this portion?

>   struct rmid_read {
>   	struct rdtgroup		*rgrp;
>   	struct rdt_resource	*r;
>   	struct rdt_mon_domain	*d;
>   	enum resctrl_event_id	evtid;
>   	bool			first;
> +	struct cacheinfo	*ci;
>   	int			err;
>   	u64			val;
>   	void			*arch_mon_ctx;

Reinette