linux-kernel - Re: [PATCH v6 17/22] x86/resctrl: Assign/unassign counters by default when ABMC is enabled

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Message-ID: <6d2dd646-49c0-4d7a-90da-10919f617e77@intel.com>
Date: Fri, 16 Aug 2024 14:42:00 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Babu Moger <babu.moger@....com>, <corbet@....net>, <fenghua.yu@...el.com>,
	<tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
	<dave.hansen@...ux.intel.com>
CC: <x86@...nel.org>, <hpa@...or.com>, <paulmck@...nel.org>,
	<rdunlap@...radead.org>, <tj@...nel.org>, <peterz@...radead.org>,
	<yanjiewtw@...il.com>, <kim.phillips@....com>, <lukas.bulwahn@...il.com>,
	<seanjc@...gle.com>, <jmattson@...gle.com>, <leitao@...ian.org>,
	<jpoimboe@...nel.org>, <rick.p.edgecombe@...el.com>,
	<kirill.shutemov@...ux.intel.com>, <jithu.joseph@...el.com>,
	<kai.huang@...el.com>, <kan.liang@...ux.intel.com>,
	<daniel.sneddon@...ux.intel.com>, <pbonzini@...hat.com>,
	<sandipan.das@....com>, <ilpo.jarvinen@...ux.intel.com>,
	<peternewman@...gle.com>, <maciej.wieczor-retman@...el.com>,
	<linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<eranian@...gle.com>, <james.morse@....com>
Subject: Re: [PATCH v6 17/22] x86/resctrl: Assign/unassign counters by default
 when ABMC is enabled

Hi Babu,

On 8/6/24 3:00 PM, Babu Moger wrote:
> Assign/unassign counters on resctrl group creation/deletion. Two counters
> are required per group, one for total event and one for local event.
> 
> There are only limited number of counters for assignment. If the counters
> are exhausted, report the warnings and continue. It is not required to

Regarding "report the warnings and continue", which warnings are you referring to?

> fail group creation for assignment failures. Users have the option to
> modify the assignments later.
> 
> Signed-off-by: Babu Moger <babu.moger@....com>
> ---
> v6: Removed the redundant comments on all the calls of
>      rdtgroup_assign_cntrs. Updated the commit message.
>      Dropped printing error message on every call of rdtgroup_assign_cntrs.
> 
> v5: Removed the code to enable/disable ABMC during the mount.
>      That will be another patch.
>      Added arch callers to get the arch specific data.
>      Renamed fuctions to match the other abmc function.
>      Added code comments for assignment failures.
> 
> v4: Few name changes based on the upstream discussion.
>      Commit message update.
> 
> v3: This is a new patch. Patch addresses the upstream comment to enable
>      ABMC feature by default if the feature is available.
> ---
>   arch/x86/kernel/cpu/resctrl/rdtgroup.c | 55 ++++++++++++++++++++++++++
>   1 file changed, 55 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 0c2215dbd497..d93c1d784b91 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -2908,6 +2908,46 @@ static void schemata_list_destroy(void)
>   	}
>   }
>   
> +/*
> + * Called when new group is created. Assign the counters if ABMC is

Please replace ABMC with resctrl fs generic terms.

> + * already enabled. Two counters are required per group, one for total
> + * event and one for local event. With limited number of counters,
> + * the assignments can fail in some cases. But, it is not required to
> + * fail the group creation. Users have the option to modify the
> + * assignments after the group creation.
> + */
> +static int rdtgroup_assign_cntrs(struct rdtgroup *rdtgrp)
> +{
> +	int ret = 0;
> +
> +	if (!resctrl_arch_get_abmc_enabled())
> +		return 0;
> +
> +	if (is_mbm_total_enabled())
> +		ret = rdtgroup_assign_cntr(rdtgrp, QOS_L3_MBM_TOTAL_EVENT_ID);
> +
> +	if (!ret && is_mbm_local_enabled())
> +		ret = rdtgroup_assign_cntr(rdtgrp, QOS_L3_MBM_LOCAL_EVENT_ID);
> +
> +	return ret;
> +}
> +

Reinette