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Message-ID: <acb1a461-1e2d-40fb-80f5-fbb6a81145e1@intel.com>
Date: Tue, 15 Oct 2024 20:14:55 -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 v8 10/25] x86/resctrl: Introduce bitmap mbm_cntr_free_map
to track assignable counters
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*.
>
> 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.
> +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.
> 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
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