Re: [PATCH v3 08/10] x86/resctrl: Add the sysfs interface to read the event configuration

[Reinette Chatre]

Hi Babu,

On 8/22/2022 6:44 AM, Babu Moger wrote:
> The current event configuration can be viewed by the user by reading
> the sysfs configuration file.
> 
> Following are the types of events supported.
> ====================================================================
> Bits    Description
> 6       Dirty Victims from the QOS domain to all types of memory
> 5       Reads to slow memory in the non-local NUMA domain
> 4       Reads to slow memory in the local NUMA domain
> 3       Non-temporal writes to non-local NUMA domain
> 2       Non-temporal writes to local NUMA domain
> 1       Reads to memory in the non-local NUMA domain
> 0       Reads to memory in the local NUMA domain
> 
> By default the mbm_total_bytes configuration is set to 0x7f to count
> all the types of events and mbm_local_bytes configuration is set to
> 0x15 to count all the local memory events.
> 
> $cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_total_config
> 0x7f
> 
> $cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_local_config
> 0x15
> 
> Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
> Reviewed-by: Ingo Molnar <mingo@xxxxxxxxxx>
> ---
>  arch/x86/kernel/cpu/resctrl/internal.h |   21 ++++++++++
>  arch/x86/kernel/cpu/resctrl/rdtgroup.c |   70 ++++++++++++++++++++++++++++++++
>  2 files changed, 91 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index fc725f5e9024..457666709386 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -15,6 +15,7 @@
>  #define MSR_IA32_MBA_THRTL_BASE		0xd50
>  #define MSR_IA32_MBA_BW_BASE		0xc0000200
>  #define MSR_IA32_SMBA_BW_BASE		0xc0000280
> +#define MSR_IA32_EVT_CFG_BASE		0xc0000400
>  
>  #define MSR_IA32_QM_CTR			0x0c8e
>  #define MSR_IA32_QM_EVTSEL		0x0c8d
> @@ -50,6 +51,26 @@
>   */
>  #define MBM_CNTR_WIDTH_OFFSET_MAX (62 - MBM_CNTR_WIDTH_BASE)
>  
> +/* Reads to Local DRAM Memory */
> +#define READS_TO_LOCAL_MEM		BIT(0)
> +
> +/* Reads to Remote DRAM Memory */
> +#define READS_TO_REMOTE_MEM		BIT(1)
> +
> +/* Non-Temporal Writes to Local Memory */
> +#define NON_TEMP_WRITE_TO_LOCAL_MEM	BIT(2)
> +
> +/* Non-Temporal Writes to Remote Memory */
> +#define NON_TEMP_WRITE_TO_REMOTE_MEM	BIT(3)
> +
> +/* Reads to Local Memory the system identifies as "Slow Memory" */
Seems unexpected character slipped into "identifies".

> +#define READS_TO_LOCAL_S_MEM		BIT(4)
> +
> +/* Reads to Remote Memory the system identifies as "Slow Memory" */

here also

> +#define READS_TO_REMOTE_S_MEM		BIT(5)
> +
> +/* Dirty Victims to All Types of Memory */
> +#define  DIRTY_VICTIS_TO_ALL_MEM	BIT(6)

Is this intended to be "DIRTY_VICTIMS_TO_ALL_MEM" ?

>  
>  struct rdt_fs_context {
>  	struct kernfs_fs_context	kfc;
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 30d2182d4fda..e1847d49fa15 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -254,8 +254,78 @@ static const struct kernfs_ops kf_mondata_ops = {
>  	.seq_show		= rdtgroup_mondata_show,
>  };
>  
> +/*
> + * This is called via IPI to read the CQM/MBM counters
> + * in a domain.
> + */
> +void mon_event_config_read(void *info)
> +{
> +	union mon_data_bits *md = info;
> +	u32 evtid = md->u.evtid;
> +	u32 h, msr_index;
> +
> +	switch (evtid) {
> +	case QOS_L3_MBM_TOTAL_EVENT_ID:
> +		msr_index = 0;
> +		break;
> +	case QOS_L3_MBM_LOCAL_EVENT_ID:
> +		msr_index = 1;
> +		break;
> +	default:
> +		return; /* Not expected to come here */

Please no inline comments.

> +	}
> +
> +	rdmsr(MSR_IA32_EVT_CFG_BASE + msr_index, md->u.mon_config, h);
> +}
> +
> +void mondata_config_read(struct rdt_domain *d, union mon_data_bits *md)
> +{
> +	smp_call_function_any(&d->cpu_mask, mon_event_config_read, md, 1);
> +}
> +
> +int rdtgroup_mondata_config_show(struct seq_file *m, void *arg)
> +{
> +	struct kernfs_open_file *of = m->private;
> +	struct rdt_hw_resource *hw_res;
> +	u32 resid, evtid, domid;
> +	struct rdtgroup *rdtgrp;
> +	struct rdt_resource *r;
> +	union mon_data_bits md;
> +	struct rdt_domain *d;
> +	int ret = 0;
> +
> +	rdtgrp = rdtgroup_kn_lock_live(of->kn);
> +	if (!rdtgrp) {
> +		ret = -ENOENT;
> +		goto out;
> +	}
> +
> +	md.priv = of->kn->priv;
> +	resid = md.u.rid;
> +	domid = md.u.domid;
> +	evtid = md.u.evtid;
> +
> +	hw_res = &rdt_resources_all[resid];
> +	r = &hw_res->r_resctrl;
> +
> +	d = rdt_find_domain(r, domid, NULL);
> +	if (IS_ERR_OR_NULL(d)) {
> +		ret = -ENOENT;
> +		goto out;
> +	}
> +
> +	mondata_config_read(d, &md);
> +
> +	seq_printf(m, "0x%x\n", md.u.mon_config);

Looking at this patch and the next, the sysfs files are introduced to read
from and write to the configuration register. From what I can tell the
data is never used internally (what did I miss?). Why is the value of the
configuration register stored? 

> +
> +out:
> +	rdtgroup_kn_unlock(of->kn);
> +	return ret;
> +}
> +
>  static const struct kernfs_ops kf_mondata_config_ops = {
>  	.atomic_write_len       = PAGE_SIZE,
> +	.seq_show               = rdtgroup_mondata_config_show,
>  };
>  
>  static bool is_cpu_list(struct kernfs_open_file *of)
> 
> 


Reinette