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Message-ID: <7375cacc-5800-487c-bd8a-7ea11e694598@amd.com>
Date: Fri, 7 Feb 2025 12:23:02 -0600
From: "Moger, Babu" <bmoger@....com>
To: Reinette Chatre <reinette.chatre@...el.com>,
Babu Moger <babu.moger@....com>, corbet@....net, tglx@...utronix.de,
mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
tony.luck@...el.com, peternewman@...gle.com
Cc: x86@...nel.org, hpa@...or.com, paulmck@...nel.org,
akpm@...ux-foundation.org, thuth@...hat.com, rostedt@...dmis.org,
xiongwei.song@...driver.com, pawan.kumar.gupta@...ux.intel.com,
daniel.sneddon@...ux.intel.com, jpoimboe@...nel.org, perry.yuan@....com,
sandipan.das@....com, kai.huang@...el.com, xiaoyao.li@...el.com,
seanjc@...gle.com, xin3.li@...el.com, andrew.cooper3@...rix.com,
ebiggers@...gle.com, mario.limonciello@....com, james.morse@....com,
tan.shaopeng@...itsu.com, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org, maciej.wieczor-retman@...el.com,
eranian@...gle.com
Subject: Re: [PATCH v11 11/23] x86/resctrl: Introduce mbm_cntr_cfg to track
assignable counters at domain
Hi Reinette,
On 2/5/2025 5:57 PM, Reinette Chatre wrote:
> Hi Babu,
>
> On 1/22/25 12:20 PM, Babu Moger wrote:
>> In mbm_cntr_assign mode hardware counters are assigned/unassigned to an
>> MBM event of a monitor group. Hardware counters are assigned/unassigned
>> at monitoring domain level.
>>
>> Manage a monitoring domain's hardware counters using a per monitoring
>> domain array of struct mbm_cntr_cfg that is indexed by the hardware
>> counter ID. A hardware counter's configuration contains the MBM event
>
> Something strange in this changelog with a few random \t in the text.
Not sure how it got in there. I can only see with "set list" option.
I Will remove it.
>
>> ID and points to the monitoring group that it is assigned to, with a
>> NULL pointer meaning that the hardware counter is available for assignment.
>>
>> There is no direct way to determine which hardware counters are assigned
>
> ... another \t above
Sure.
>
>> to a particular monitoring group. Check every entry of every hardware
>> counter configuration array in every monitoring domain to query which
>
> ... one more \t above
Sure
>
>> MBM events of a monitoring group is tracked by hardware. Such queries
>> are acceptable because of a very small number of assignable counters.
>
> It is not obvious what "very small number" means. Is it possible to give
> a range to help reader understand the motivation?
How about?
MBM events of a monitoring group is tracked by hardware. Such queries
are acceptable because of a very small number of assignable counters(32
to 64).
>
>>
>> Suggested-by: Peter Newman <peternewman@...gle.com>
>> Signed-off-by: Babu Moger <babu.moger@....com>
>> ---
>
>> ---
>> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 11 +++++++++++
>> include/linux/resctrl.h | 14 ++++++++++++++
>> 2 files changed, 25 insertions(+)
>>
>> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> index 18110a1afb6d..75a3b56996ca 100644
>> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> @@ -4009,6 +4009,7 @@ static void __init rdtgroup_setup_default(void)
>>
>> static void domain_destroy_mon_state(struct rdt_mon_domain *d)
>> {
>> + kfree(d->cntr_cfg);
>> bitmap_free(d->rmid_busy_llc);
>> kfree(d->mbm_total);
>> kfree(d->mbm_local);
>> @@ -4082,6 +4083,16 @@ static int domain_setup_mon_state(struct rdt_resource *r, struct rdt_mon_domain
>> return -ENOMEM;
>> }
>> }
>> + if (is_mbm_enabled() && r->mon.mbm_cntr_assignable) {
>> + tsize = sizeof(*d->cntr_cfg);
>> + d->cntr_cfg = kcalloc(r->mon.num_mbm_cntrs, tsize, GFP_KERNEL);
>> + if (!d->cntr_cfg) {
>> + bitmap_free(d->rmid_busy_llc);
>> + kfree(d->mbm_total);
>> + kfree(d->mbm_local);
>> + return -ENOMEM;
>> + }
>> + }
>>
>> return 0;
>> }
>> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
>> index 511cfce8fc21..9a54e307d340 100644
>> --- a/include/linux/resctrl.h
>> +++ b/include/linux/resctrl.h
>> @@ -94,6 +94,18 @@ struct rdt_ctrl_domain {
>> u32 *mbps_val;
>> };
>>
>> +/**
>> + * struct mbm_cntr_cfg - assignable counter configuration
>> + * @evtid: MBM event to which the counter is assigned. Only valid
>> + * if @rdtgroup is not NULL.
>> + * @rdtgroup: resctrl group assigned to the counter. NULL if the
>> + * counter is free.
>> + */
>> +struct mbm_cntr_cfg {
>> + enum resctrl_event_id evtid;
>> + struct rdtgroup *rdtgrp;
>> +};
>> +
>
> $ scripts/kernel-doc -v -none include/linux/resctrl.h
> ...
> include/linux/resctrl.h:107: warning: Function parameter or struct member 'rdtgrp' not described in 'mbm_cntr_cfg'
> include/linux/resctrl.h:107: warning: Excess struct member 'rdtgroup' description in 'mbm_cntr_cfg'
Yes. Will fix this.
> ...
>
>> /**
>> * struct rdt_mon_domain - group of CPUs sharing a resctrl monitor resource
>> * @hdr: common header for different domain types
>> @@ -105,6 +117,7 @@ struct rdt_ctrl_domain {
>> * @cqm_limbo: worker to periodically read CQM h/w counters
>> * @mbm_work_cpu: worker CPU for MBM h/w counters
>> * @cqm_work_cpu: worker CPU for CQM h/w counters
>> + * @cntr_cfg: assignable counters configuration
>> */
>> struct rdt_mon_domain {
>> struct rdt_domain_hdr hdr;
>> @@ -116,6 +129,7 @@ struct rdt_mon_domain {
>> struct delayed_work cqm_limbo;
>> int mbm_work_cpu;
>> int cqm_work_cpu;
>> + struct mbm_cntr_cfg *cntr_cfg;
>> };
>>
>> /**
>
> Reinette
>
>
Thanks
Babu
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