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Message-ID: <5b02cab6-d539-41a9-af1a-e0fee1b9a74d@amd.com>
Date: Fri, 20 Dec 2024 11:33:12 -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: fenghua.yu@...el.com, 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,
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 v10 12/24] x86/resctrl: Introduce cntr_cfg to track
assignable counters at domain
Hi Reinette,
On 12/19/2024 4:33 PM, Reinette Chatre wrote:
> Hi Babu,
>
> Did subject intend to use name of new struct?
Yes. Will change it to "mbm_cntr_cfg.
>
> On 12/12/24 12:15 PM, Babu Moger wrote:
>> In mbm_assign_mode, the MBM counters are assigned/unassigned to an RMID,
>> event pair in a resctrl group and monitor the bandwidth as long as it is
>> assigned. Counters are assigned/unassigned at domain level and needs to
>> be tracked at domain level.
>>
>> Add the mbm_assign_cntr_cfg data structure to struct rdt_ctrl_domain to
>
> "mbm_assign_cntr_cfg" -> "mbm_cntr_cfg"
Sure.
>
>> manage and track MBM counter assignments at the domain level.
>
> This can really use some more information about this data structure. I think
> it will be helpful to provide more information about how the data structure
> looks ... for example, that it is an array indexed by counter ID where the
> assignment details of each counter is stored. I also think it will be helpful
> to describe how interactions with this data structure works, that a NULL
> rdtgrp means that the counter is free and that it is not possible to find
> a counter from a resource group and arrays need to be searched instead and doing
> so is ok for $REASON (when considering the number of RMID and domain combinations
> possible on AMD). A lot is left for the reader to figure out.
How about this?
In mbm_assign_mode, the MBM counters are assigned/unassigned to an RMID,
event pair in a resctrl group and monitor the bandwidth as long as it is
assigned. Counters are assigned/unassigned at domain level and needs to
be tracked at domain level.
Add the mbm_cntr_cfg data structure to struct rdt_ctrl_domain to
manage and track MBM counter assignments at the domain level.
Each domain will contain num_mbm_cntrs entries, indexed by cntr_id.
During initialization, all entries will be set to zero. When a counter
is allocated, its corresponding entry will be populated with the
assigned struct rdtgroup and enum resctrl_event_id. When the counter is
released, its entry will be reset to zero.
>>
>> Suggested-by: Peter Newman <peternewman@...gle.com>
>> Signed-off-by: Babu Moger <babu.moger@....com>
>> ---
>> v10: Patch changed completely to handle the counters at domain level.
>> https://lore.kernel.org/lkml/CALPaoCj+zWq1vkHVbXYP0znJbe6Ke3PXPWjtri5AFgD9cQDCUg@mail.gmail.com/
>> Removed Reviewed-by tag.
>> Did not see the need to add cntr_id in mbm_state structure. Not used in the code.
>>
>> v9: Added Reviewed-by tag. No other changes.
>>
>> v8: Minor commit message changes.
>>
>> v7: Added check mbm_cntr_assignable for allocating bitmap mbm_cntr_map
>>
>> v6: New patch to add domain level assignment.
>> ---
>> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 11 +++++++++++
>> include/linux/resctrl.h | 12 ++++++++++++
>> 2 files changed, 23 insertions(+)
>>
>> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> index 682f47e0beb1..1ee008a63d8b 100644
>> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> @@ -4068,6 +4068,7 @@ 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);
>> @@ -4141,6 +4142,16 @@ 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 c8ab3d7a0dab..03c67d9156f3 100644
>> --- a/include/linux/resctrl.h
>> +++ b/include/linux/resctrl.h
>> @@ -94,6 +94,16 @@ struct rdt_ctrl_domain {
>> u32 *mbps_val;
>> };
>>
>> +/**
>> + * struct mbm_cntr_cfg -Assignable counter configuration
>
> Please compare with style use in rest of the file. For example,
> "-Assignable" -> "- assignable"
Sure.
>
>> + * @evtid: Event type
>
> This description is not useful. Consider: "MBM event to which
> the counter is assigned. Only valid if @rdtgroup is not NULL."
> (This was the first thing that came to my mind, please improve)
>
>> + * @rdtgroup: Resctrl group assigned to the counter
>
> Can add "NULL if counter is free"
Sure.
>
>> + */
>> +struct mbm_cntr_cfg {
>> + enum resctrl_event_id evtid;
>> + struct rdtgroup *rdtgrp;
>> +};
>> +
>> /**
>> * struct rdt_mon_domain - group of CPUs sharing a resctrl monitor resource
>> * @hdr: common header for different domain types
>> @@ -105,6 +115,7 @@ 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
>
> Match capitalization of surrounding text.
> Will be helpful to add that this is an array indexed by counter ID.
ok. Sure.
>
>> */
>> struct rdt_mon_domain {
>> struct rdt_domain_hdr hdr;
>> @@ -116,6 +127,7 @@ struct rdt_mon_domain {
>> struct delayed_work cqm_limbo;
>> int mbm_work_cpu;
>> int cqm_work_cpu;
>> + struct mbm_cntr_cfg *cntr_cfg;
>> };
>>
>> /**
>
> Reinette
>
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