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From: Reinette Chatre <reinette.chatre@intel.com>
To: James Morse <james.morse@arm.com>, <x86@kernel.org>,
	<linux-kernel@vger.kernel.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	H Peter Anvin <hpa@zytor.com>, Babu Moger <Babu.Moger@amd.com>,
	<shameerali.kolothum.thodi@huawei.com>,
	Jamie Iles <jamie@nuviainc.com>,
	"D Scott Phillips OS" <scott@os.amperecomputing.com>,
	<lcherian@marvell.com>, <bobo.shaobowang@huawei.com>
Subject: Re: [PATCH v1 09/20] x86/resctrl: Abstract and use supports_mba_mbps()
Date: Wed, 1 Sep 2021 14:27:26 -0700	[thread overview]
Message-ID: <c8ef35f7-efa1-0e2f-e1ab-7b0df4a5ae2d@intel.com> (raw)
In-Reply-To: <20210729223610.29373-10-james.morse@arm.com>

Hi James,

On 7/29/2021 3:35 PM, James Morse wrote:
> To determine whether the mba_mbps option to resctrl should be supported,

mba_mbps -> mba_MBps

> resctrl tests the boot cpus' x86_vendor.

CPU

> 
> This isn't portable, and needs abstracting behind a helper so this check
> can be part of the filesystem code that moves to /fs/.
> 
> Re-use the tests set_mba_sc() does to determine if the mba_sc is supported
> on this system. An 'alloc_capable' test is added so that this property
> isn't implied by 'linear'.

Why can linear not imply alloc_capable? It is a property of a MBA 
resource so if it is set then it has to be a MBA resource.

> 
> Signed-off-by: James Morse <james.morse@arm.com>
> ---
>   arch/x86/kernel/cpu/resctrl/rdtgroup.c | 19 ++++++++++++++-----
>   1 file changed, 14 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index e321ea5de562..4388685548a0 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -1888,17 +1888,26 @@ void rdt_domain_reconfigure_cdp(struct rdt_resource *r)
>   }
>   
>   /*
> - * Enable or disable the MBA software controller
> - * which helps user specify bandwidth in MBps.
>    * MBA software controller is supported only if
>    * MBM is supported and MBA is in linear scale.
>    */
> +static bool supports_mba_mbps(void)
> +{
> +	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl;
> +
> +	return (is_mbm_enabled() &&
> +		r->alloc_capable && is_mba_linear());

As mentioned above I do not see need for the alloc_capable check since 
this is hardcoded to be a MBA resource for which delay_linear can only 
be set if alloc_capable is set.

> +}
> +
> +/*
> + * Enable or disable the MBA software controller
> + * which helps user specify bandwidth in MBps.
> + */
>   static int set_mba_sc(bool mba_sc)
>   {
>   	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl;
>   
> -	if (!is_mbm_enabled() || !is_mba_linear() ||
> -	    mba_sc == is_mba_sc(r))
> +	if (!supports_mba_mbps() || mba_sc == is_mba_sc(r))
>   		return -EINVAL;
>   
>   	r->membw.mba_sc = mba_sc;
> @@ -2317,7 +2326,7 @@ static int rdt_parse_param(struct fs_context *fc, struct fs_parameter *param)
>   		ctx->enable_cdpl2 = true;
>   		return 0;
>   	case Opt_mba_mbps:
> -		if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)

I am not familiar with the history but it looks like AMD does not 
support linear (based on __rdt_get_mem_config_amd()) which may be the 
reason for this test and thus moving it to a feature check is ok.

> +		if (supports_mba_mbps())
>   			return -EINVAL;
>   		ctx->enable_mba_mbps = true;
>   		return 0;
> 

Reinette

  reply	other threads:[~2021-09-01 21:27 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-29 22:35 [PATCH v1 00/20] x86/resctrl: Make resctrl_arch_rmid_read() return values in bytes James Morse
2021-07-29 22:35 ` [PATCH v1 01/20] x86/resctrl: Kill off alloc_enabled James Morse
2021-08-11 12:12   ` Jamie Iles
2021-09-01 21:18   ` Reinette Chatre
2021-07-29 22:35 ` [PATCH v1 02/20] x86/resctrl: Merge mon_capable and mon_enabled James Morse
2021-08-11 12:15   ` Jamie Iles
2021-08-11 15:16     ` James Morse
2021-07-29 22:35 ` [PATCH v1 03/20] x86/resctrl: Add domain online callback for resctrl work James Morse
2021-09-01 21:19   ` Reinette Chatre
2021-09-17 16:57     ` James Morse
2021-07-29 22:35 ` [PATCH v1 04/20] x86/resctrl: Add domain offline " James Morse
2021-08-11 16:10   ` Jamie Iles
2021-09-01 21:21   ` Reinette Chatre
2021-07-29 22:35 ` [PATCH v1 05/20] x86/resctrl: Create mba_sc configuration in the rdt_domain James Morse
2021-08-11 16:32   ` Jamie Iles
2021-08-31 16:24     ` James Morse
2021-09-01 21:22   ` Reinette Chatre
2021-09-17 16:57     ` James Morse
2021-07-29 22:35 ` [PATCH v1 06/20] x86/resctrl: Switch over to the resctrl mbps_val list James Morse
2021-09-01 21:25   ` Reinette Chatre
2021-09-17 16:57     ` James Morse
2021-09-17 18:20       ` Reinette Chatre
2021-10-01 16:02         ` James Morse
2021-07-29 22:35 ` [PATCH v1 07/20] x86/resctrl: Remove architecture copy of mbps_val James Morse
2021-09-01 21:26   ` Reinette Chatre
2021-09-17 16:57     ` James Morse
2021-07-29 22:35 ` [PATCH v1 08/20] x86/resctrl: Remove set_mba_sc()s control array re-initialisation James Morse
2021-07-29 22:35 ` [PATCH v1 09/20] x86/resctrl: Abstract and use supports_mba_mbps() James Morse
2021-09-01 21:27   ` Reinette Chatre [this message]
2021-09-17 16:57     ` James Morse
2021-09-24  6:23   ` tan.shaopeng
2021-10-01 16:01     ` James Morse
2021-07-29 22:36 ` [PATCH v1 10/20] x86/resctrl: Allow update_mba_bw() to update controls directly James Morse
2021-09-01 21:28   ` Reinette Chatre
2021-07-29 22:36 ` [PATCH v1 11/20] x86/resctrl: Calculate bandwidth from the total bytes counter James Morse
2021-09-01 21:31   ` Reinette Chatre
2021-09-17 16:58     ` James Morse
2021-07-29 22:36 ` [PATCH v1 12/20] x86/recstrl: Add per-rmid arch private storage for overflow and chunks James Morse
2021-08-11 17:14   ` Jamie Iles
2021-08-31 16:25     ` James Morse
2021-07-29 22:36 ` [PATCH v1 13/20] x86/recstrl: Allow per-rmid arch private storage to be reset James Morse
2021-09-24  6:34   ` tan.shaopeng
2021-10-01 16:01     ` James Morse
2021-07-29 22:36 ` [PATCH v1 14/20] x86/resctrl: Abstract __rmid_read() James Morse
2021-07-29 22:36 ` [PATCH v1 15/20] x86/resctrl: Pass the required parameters into resctrl_arch_rmid_read() James Morse
2021-07-29 22:36 ` [PATCH v1 16/20] x86/resctrl: Move mbm_overflow_count() " James Morse
2021-07-29 22:36 ` [PATCH v1 17/20] x86/resctrl: Move get_corrected_mbm_count() " James Morse
2021-07-29 22:36 ` [PATCH v1 18/20] x86/resctrl: Rename and change the units of resctrl_cqm_threshold James Morse
2021-07-29 22:36 ` [PATCH v1 19/20] x86/resctrl: Add resctrl_rmid_realloc_limit to abstract x86's boot_cpu_data James Morse
2021-07-29 22:36 ` [PATCH v1 20/20] x86/resctrl: Make resctrl_arch_rmid_read() return values in bytes James Morse

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