Re: [PATCH v7 06/12] x86/resctrl: Introduce data structure to support monitor configuration

[Reinette Chatre]

Hi Babu,

On 10/17/2022 3:26 PM, Babu Moger wrote:
> Add a new field in mon_evt to support Bandwidth Monitoring Event
> Configuration(BMEC) and also update the "mon_features" display.
> 
> The sysfs file "mon_features" will display the monitor configuration
> if supported.
> 
> Before the change.
> 	$cat /sys/fs/resctrl/info/L3_MON/mon_features
> 	llc_occupancy
> 	mbm_total_bytes
> 	mbm_local_bytes
> 
> After the change if BMEC is supported.
> 	$cat /sys/fs/resctrl/info/L3_MON/mon_features
> 	llc_occupancy
> 	mbm_total_bytes
> 	mbm_total_config
> 	mbm_local_bytes
> 	mbm_local_config

This does not seem to be what the code in this patch does.

> 
> Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
> ---
>  arch/x86/kernel/cpu/resctrl/core.c     |    3 ++-
>  arch/x86/kernel/cpu/resctrl/internal.h |    4 +++-
>  arch/x86/kernel/cpu/resctrl/monitor.c  |    7 ++++++-
>  arch/x86/kernel/cpu/resctrl/rdtgroup.c |    5 ++++-
>  4 files changed, 15 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
> index d79f494a4e91..46813b1c50c2 100644
> --- a/arch/x86/kernel/cpu/resctrl/core.c
> +++ b/arch/x86/kernel/cpu/resctrl/core.c
> @@ -814,6 +814,7 @@ static __init bool get_rdt_alloc_resources(void)
>  static __init bool get_rdt_mon_resources(void)
>  {
>  	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
> +	bool mon_configurable = rdt_cpu_has(X86_FEATURE_BMEC);
>  
>  	if (rdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC))
>  		rdt_mon_features |= (1 << QOS_L3_OCCUP_EVENT_ID);
> @@ -825,7 +826,7 @@ static __init bool get_rdt_mon_resources(void)
>  	if (!rdt_mon_features)
>  		return false;
>  
> -	return !rdt_get_mon_l3_config(r);
> +	return !rdt_get_mon_l3_config(r, mon_configurable);
>  }

This seems to do a portion of configuration in the calling function, pass the
results of to the actual configuration function where the rest of the configuration is
done. Determining "mon_configurable" really looks like it belongs in 
rdt_get_mon_l3_config(). Is it availability of rdt_cpu_has() that prevented
that change? Why not make it available internally to all resctrl code?

Patch 7's mbm_config_rftype_init() can also be moved to rdt_get_mon_l3_config()
to match how other related configs (thread_throttle_mode_init()) are done.

>  
>  static __init void __check_quirks_intel(void)
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 16e3c6e03c79..b458f768f30c 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -63,11 +63,13 @@ DECLARE_STATIC_KEY_FALSE(rdt_mon_enable_key);
>   * struct mon_evt - Entry in the event list of a resource
>   * @evtid:		event id
>   * @name:		name of the event
> + * @configurable:	true if the event is configurable
>   * @list:		entry in &rdt_resource->evt_list
>   */
>  struct mon_evt {
>  	enum resctrl_event_id	evtid;
>  	char			*name;
> +	bool			configurable;
>  	struct list_head	list;
>  };
>  
> @@ -522,7 +524,7 @@ int closids_supported(void);
>  void closid_free(int closid);
>  int alloc_rmid(void);
>  void free_rmid(u32 rmid);
> -int rdt_get_mon_l3_config(struct rdt_resource *r);
> +int rdt_get_mon_l3_config(struct rdt_resource *r, bool configurable);
>  void mon_event_count(void *info);
>  int rdtgroup_mondata_show(struct seq_file *m, void *arg);
>  void mon_event_read(struct rmid_read *rr, struct rdt_resource *r,
> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
> index efe0c30d3a12..4b8adb7f1c5c 100644
> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> @@ -746,7 +746,7 @@ static void l3_mon_evt_init(struct rdt_resource *r)
>  		list_add_tail(&mbm_local_event.list, &r->evt_list);
>  }
>  
> -int rdt_get_mon_l3_config(struct rdt_resource *r)
> +int rdt_get_mon_l3_config(struct rdt_resource *r, bool configurable)
>  {
>  	unsigned int mbm_offset = boot_cpu_data.x86_cache_mbm_width_offset;
>  	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
> @@ -783,6 +783,11 @@ int rdt_get_mon_l3_config(struct rdt_resource *r)
>  	if (ret)
>  		return ret;
>  
> +	if (configurable) {
> +		mbm_total_event.configurable = true;
> +		mbm_local_event.configurable = true;
> +	}
> +
>  	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 1271fd1ae2f3..5f0ef1bf4c78 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -1001,8 +1001,11 @@ static int rdt_mon_features_show(struct kernfs_open_file *of,
>  	struct rdt_resource *r = of->kn->parent->priv;
>  	struct mon_evt *mevt;
>  
> -	list_for_each_entry(mevt, &r->evt_list, list)
> +	list_for_each_entry(mevt, &r->evt_list, list) {
>  		seq_printf(seq, "%s\n", mevt->name);
> +		if (mevt->configurable)
> +			seq_printf(seq, "%s_config\n", mevt->name);
> +	}
>  
>  	return 0;
>  }
> 

If mevt->name is "mbm_total_bytes", then would this not
print "mbm_total_bytes_config"? This is different from "mbm_total_config"
in the changelog and does not match the actual files created in later
patches..

Reinette