linux-kernel - Re: [PATCH v4 3/4] x86/resctrl: Add sparse

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Date:   Fri, 6 Oct 2023 09:30:37 -0500
From:   "Moger, Babu" <bmoger@....com>
To:     Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>
Cc:     Peter Newman <peternewman@...gle.com>,
        Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 3/4] x86/resctrl: Add sparse_masks file in info


On 10/5/2023 3:15 AM, Maciej Wieczor-Retman wrote:
> From: Fenghua Yu <fenghua.yu@...el.com>
>
> Add the interface in resctrl FS to show if sparse cache allocation
> bit masks are supported on the platform. Reading the file returns
> either a "1" if non-contiguous 1s are supported and "0" otherwise.
> The file path is /sys/fs/resctrl/info/{resource}/sparse_masks, where
> {resource} can be either "L2" or "L3".
>
> Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
> Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>
> Tested-by: Peter Newman <peternewman@...gle.com>
> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
> Reviewed-by: Peter Newman <peternewman@...gle.com>
> Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>
Reviewed-by: Babu Moger <babu.moger@....com>
> ---
> Changelog v4:
> - Add Ilpo's reviewed-by tag.
> - Add Reinette's reviewed-by tag.
>
> Changelog v3:
> - Add Peter's tested-by and reviewed-by tags.
> - Reword patch message slightly. (Reinette)
>
> Changelog v2:
> - Change bitmap naming convention to bit mask. (Reinette)
> - Change file name to "sparse_masks". (Reinette)
>
>   arch/x86/kernel/cpu/resctrl/rdtgroup.c | 18 ++++++++++++++++++
>   1 file changed, 18 insertions(+)
>
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 725344048f85..945801898a4d 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -895,6 +895,17 @@ static int rdt_shareable_bits_show(struct kernfs_open_file *of,
>   	return 0;
>   }
>   
> +static int rdt_has_sparse_bitmasks_show(struct kernfs_open_file *of,
> +					struct seq_file *seq, void *v)
> +{
> +	struct resctrl_schema *s = of->kn->parent->priv;
> +	struct rdt_resource *r = s->res;
> +
> +	seq_printf(seq, "%u\n", r->cache.arch_has_sparse_bitmasks);
> +
> +	return 0;
> +}
> +
>   /**
>    * rdt_bit_usage_show - Display current usage of resources
>    *
> @@ -1839,6 +1850,13 @@ static struct rftype res_common_files[] = {
>   		.seq_show	= rdtgroup_size_show,
>   		.fflags		= RF_CTRL_BASE,
>   	},
> +	{
> +		.name		= "sparse_masks",
> +		.mode		= 0444,
> +		.kf_ops		= &rdtgroup_kf_single_ops,
> +		.seq_show	= rdt_has_sparse_bitmasks_show,
> +		.fflags		= RF_CTRL_INFO | RFTYPE_RES_CACHE,
> +	},
>   
>   };
>