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Message-ID: <b1e66a52-7065-49f3-bc24-9460ed1b8449@amd.com>
Date: Thu, 17 Oct 2024 11:55:20 -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 10/25] x86/resctrl: Introduce bitmap mbm_cntr_free_map
to track assignable counters
Hi Reinette,
On 10/15/24 22:14, Reinette Chatre wrote:
> Hi Babu,
>
> On 10/9/24 10:39 AM, Babu Moger wrote:
>> Hardware provides a set of counters when mbm_assign_mode is supported.
>> These counters are assigned to the MBM monitoring events of a MON group
>> that needs to be tracked. The kernel must manage and track the available
>> counters.
>>
>> Introduce mbm_cntr_free_map bitmap to track available counters and set
>> of routines to allocate and free the counters. Move dom_data_init() after
>> mbm_cntr_assign detection.
>
> Regarding "Move dom_data_init() after mbm_cntr_assign detection." - this is
> clear from the patch, please use changelog to explain *why*.
Will change it to.
dom_data_init() requires mbm_cntr_assign state to initialize
mbm_cntr_free_map bitmap. Move dom_data_init() after mbm_cntr_assign
detection.
>
>>
>> Signed-off-by: Babu Moger <babu.moger@....com>
>> ---
>
>
>> ---
>> arch/x86/kernel/cpu/resctrl/internal.h | 2 ++
>> arch/x86/kernel/cpu/resctrl/monitor.c | 43 +++++++++++++++++++++++---
>> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 19 ++++++++++++
>> include/linux/resctrl.h | 2 ++
>> 4 files changed, 62 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
>> index 92eae4672312..99f9103a35ba 100644
>> --- a/arch/x86/kernel/cpu/resctrl/internal.h
>> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
>> @@ -654,6 +654,8 @@ void __check_limbo(struct rdt_mon_domain *d, bool force_free);
>> void rdt_domain_reconfigure_cdp(struct rdt_resource *r);
>> void __init resctrl_file_fflags_init(const char *config,
>> unsigned long fflags);
>> +int mbm_cntr_alloc(struct rdt_resource *r);
>> +void mbm_cntr_free(struct rdt_resource *r, u32 cntr_id);
>> void rdt_staged_configs_clear(void);
>> bool closid_allocated(unsigned int closid);
>> int resctrl_find_cleanest_closid(void);
>> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
>> index 66b06574f660..5c2a28565747 100644
>> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
>> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
>> @@ -983,6 +983,27 @@ void mbm_setup_overflow_handler(struct rdt_mon_domain *dom, unsigned long delay_
>> schedule_delayed_work_on(cpu, &dom->mbm_over, delay);
>> }
>>
>> +/*
>> + * Counter bitmap for tracking the available counters.
>> + * 'mbm_cntr_assign' mode provides set of hardware counters for assigning
>> + * RMID, event pair. Each RMID and event pair takes one hardware counter.
>> + */
>
> "counters for assigning RMID, event pair" sounds strange and it seems like the same
> thing is mentioned twice.
> How about:
> Bitmap tracking the available hardware counters when operating in
> "mbm_cntr_assign" mode. A hardware counter can be assigned to a
> RMID, event pair.
Sure.
>
>> +static __init unsigned long *mbm_cntrs_init(struct rdt_resource *r)
>> +{
>> + r->mon.mbm_cntr_free_map = bitmap_zalloc(r->mon.num_mbm_cntrs,
>> + GFP_KERNEL);
>> + if (r->mon.mbm_cntr_free_map)
>> + bitmap_fill(r->mon.mbm_cntr_free_map, r->mon.num_mbm_cntrs);
>> +
>> + return r->mon.mbm_cntr_free_map;
>> +}
>> +
>> +static __exit void mbm_cntrs_exit(struct rdt_resource *r)
>> +{
>> + bitmap_free(r->mon.mbm_cntr_free_map);
>> + r->mon.mbm_cntr_free_map = NULL;
>> +}
>> +
>> static __init int dom_data_init(struct rdt_resource *r)
>> {
>> u32 idx_limit = resctrl_arch_system_num_rmid_idx();
>> @@ -1020,6 +1041,17 @@ static __init int dom_data_init(struct rdt_resource *r)
>> goto out_unlock;
>> }
>>
>> + if (r->mon.mbm_cntr_assignable && !mbm_cntrs_init(r)) {
>> + if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID)) {
>> + kfree(closid_num_dirty_rmid);
>> + closid_num_dirty_rmid = NULL;
>> + }
>> + kfree(rmid_ptrs);
>> + rmid_ptrs = NULL;
>> + err = -ENOMEM;
>> + goto out_unlock;
>> + }
>> +
>> for (i = 0; i < idx_limit; i++) {
>> entry = &rmid_ptrs[i];
>> INIT_LIST_HEAD(&entry->list);
>> @@ -1056,6 +1088,9 @@ static void __exit dom_data_exit(struct rdt_resource *r)
>> kfree(rmid_ptrs);
>> rmid_ptrs = NULL;
>>
>> + if (r->mon.mbm_cntr_assignable)
>> + mbm_cntrs_exit(r);
>> +
>> mutex_unlock(&rdtgroup_mutex);
>> }
>>
>> @@ -1210,10 +1245,6 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
>> */
>> resctrl_rmid_realloc_threshold = resctrl_arch_round_mon_val(threshold);
>>
>> - ret = dom_data_init(r);
>> - if (ret)
>> - return ret;
>> -
>> if (rdt_cpu_has(X86_FEATURE_BMEC)) {
>> u32 eax, ebx, ecx, edx;
>>
>> @@ -1240,6 +1271,10 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
>> }
>> }
>>
>> + ret = dom_data_init(r);
>> + if (ret)
>> + return ret;
>> +
>> l3_mon_evt_init(r);
>>
>> r->mon_capable = true;
>> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> index c48b5450e6c2..8ffebd203c31 100644
>> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> @@ -185,6 +185,25 @@ bool closid_allocated(unsigned int closid)
>> return !test_bit(closid, &closid_free_map);
>> }
>>
>> +int mbm_cntr_alloc(struct rdt_resource *r)
>> +{
>> + int cntr_id;
>> +
>> + cntr_id = find_first_bit(r->mon.mbm_cntr_free_map,
>> + r->mon.num_mbm_cntrs);
>> + if (cntr_id >= r->mon.num_mbm_cntrs)
>> + return -ENOSPC;
>> +
>> + __clear_bit(cntr_id, r->mon.mbm_cntr_free_map);
>> +
>> + return cntr_id;
>> +}
>> +
>> +void mbm_cntr_free(struct rdt_resource *r, u32 cntr_id)
>> +{
>> + __set_bit(cntr_id, r->mon.mbm_cntr_free_map);
>> +}
>> +
>> /**
>> * rdtgroup_mode_by_closid - Return mode of resource group with closid
>> * @closid: closid if the resource group
>> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
>> index f11d6fdfd977..5a4d6adec974 100644
>> --- a/include/linux/resctrl.h
>> +++ b/include/linux/resctrl.h
>> @@ -187,12 +187,14 @@ enum resctrl_scope {
>> * @num_rmid: Number of RMIDs available
>> * @num_mbm_cntrs: Number of assignable monitoring counters
>> * @mbm_cntr_assignable:Is system capable of supporting monitor assignment?
>> + * @mbm_cntr_free_map: bitmap of free MBM counters
>> * @evt_list: List of monitoring events
>> */
>
> Please follow custom of existing doc and have description start with capital letter.
Sure.
>
>> struct resctrl_mon {
>> int num_rmid;
>> int num_mbm_cntrs;
>> bool mbm_cntr_assignable;
>> + unsigned long *mbm_cntr_free_map;
>> struct list_head evt_list;
>> };
>>
>
> Reinette
>
--
Thanks
Babu Moger
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