linux-kernel - Re: [PATCH v8 15/25] x86/resctrl: Introduce cntr

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Message-ID: <6c5c4907-0892-4f37-8d9c-7ebef3ddb314@amd.com>
Date: Thu, 17 Oct 2024 14:19:35 -0500
From: "Moger, Babu" <babu.moger@....com>
To: Reinette Chatre <reinette.chatre@...el.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,
 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 v8 15/25] x86/resctrl: Introduce cntr_id in mongroup for
 assignments

Hi Reinette,

On 10/15/24 22:22, Reinette Chatre wrote:
> Hi Babu,
> 
> On 10/9/24 10:39 AM, Babu Moger wrote:
>> mbm_cntr_assign feature provides an option to the user to assign a counter
>> to an RMID, event pair and monitor the bandwidth as long as the counter is
>> assigned. There can be two counters per monitor group, one for MBM total
>> event and another for MBM local event.
>>
>> Introduce cntr_id to manage the assignments.
>>
>> Signed-off-by: Babu Moger <babu.moger@....com>
>> ---
>> v8: Minor commit message update.
>>
>> v7: Minor comment update for cntr_id.
>>
>> v6: New patch.
>>     Separated FS and arch bits.
>> ---
>>  arch/x86/kernel/cpu/resctrl/internal.h | 7 +++++++
>>  arch/x86/kernel/cpu/resctrl/rdtgroup.c | 6 ++++++
>>  2 files changed, 13 insertions(+)
>>
>> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
>> index de397468b945..58298db9034f 100644
>> --- a/arch/x86/kernel/cpu/resctrl/internal.h
>> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
>> @@ -62,6 +62,11 @@
>>  /* Setting bit 0 in L3_QOS_EXT_CFG enables the ABMC feature. */
>>  #define ABMC_ENABLE_BIT			0
>>  
>> +/* Maximum assignable counters per resctrl group */
>> +#define MAX_CNTRS			2
>> +
>> +#define MON_CNTR_UNSET			U32_MAX
>> +
>>  /**
>>   * cpumask_any_housekeeping() - Choose any CPU in @mask, preferring those that
>>   *			        aren't marked nohz_full
>> @@ -231,12 +236,14 @@ enum rdtgrp_mode {
>>   * @parent:			parent rdtgrp
>>   * @crdtgrp_list:		child rdtgroup node list
>>   * @rmid:			rmid for this rdtgroup
>> + * @cntr_id:			IDs of hardware counters assigned to monitor group
>>   */
>>  struct mongroup {
>>  	struct kernfs_node	*mon_data_kn;
>>  	struct rdtgroup		*parent;
>>  	struct list_head	crdtgrp_list;
>>  	u32			rmid;
>> +	u32			cntr_id[MAX_CNTRS];
>>  };
>>  
>>  /**
>> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> index 610eae64b13a..03b670b95c49 100644
>> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> @@ -3530,6 +3530,9 @@ static int mkdir_rdt_prepare_rmid_alloc(struct rdtgroup *rdtgrp)
>>  	}
>>  	rdtgrp->mon.rmid = ret;
>>  
>> +	rdtgrp->mon.cntr_id[0] = MON_CNTR_UNSET;
>> +	rdtgrp->mon.cntr_id[1] = MON_CNTR_UNSET;
>> +
>>  	ret = mkdir_mondata_all(rdtgrp->kn, rdtgrp, &rdtgrp->mon.mon_data_kn);
>>  	if (ret) {
>>  		rdt_last_cmd_puts("kernfs subdir error\n");
>> @@ -4084,6 +4087,9 @@ static void __init rdtgroup_setup_default(void)
>>  	rdtgroup_default.closid = RESCTRL_RESERVED_CLOSID;
>>  	rdtgroup_default.mon.rmid = RESCTRL_RESERVED_RMID;
>>  	rdtgroup_default.type = RDTCTRL_GROUP;
>> +	rdtgroup_default.mon.cntr_id[0] = MON_CNTR_UNSET;
>> +	rdtgroup_default.mon.cntr_id[1] = MON_CNTR_UNSET;
>> +
> 
> Could these magic constants be avoided by introducing MBM_EVENT_ARRAY_INDEX here
> and using it for the array index instead of "0" and "1"?

Sure. Will do.

> 
>>  	INIT_LIST_HEAD(&rdtgroup_default.mon.crdtgrp_list);
>>  
>>  	list_add(&rdtgroup_default.rdtgroup_list, &rdt_all_groups);
> 
> Reinette
> 
> 
> 

-- 
Thanks
Babu Moger