Re: [PATCH v5 19/20] x86/resctrl: Introduce interface to list monitor states of all the groups

Reinette Chatre
2024-07-12T22:16:44Z

Hi Babu,

On 7/3/24 2:48 PM, Babu Moger wrote:
> Provide the interface to list the monitor states of all the resctrl
> groups in ABMC mode.
>
> Example:
> $cat /sys/fs/resctrl/info/L3_MON/mbm_control
>
> List follows the following format:
>
> "<CTRL_MON group>/<MON group>/<domain_id>=<flags>"
>
> Format for specific type of groups:
>
> - Default CTRL_MON group:
> "//<domain_id>=<flags>"
>
> - Non-default CTRL_MON group:
> "<CTRL_MON group>//<domain_id>=<flags>"
>
> - Child MON group of default CTRL_MON group:
> "/<MON group>/<domain_id>=<flags>"
>
> - Child MON group of non-default CTRL_MON group:
> "<CTRL_MON group>/<MON group>/<domain_id>=<flags>"
>
>
> Flags can be one of the following:
> t MBM total event is enabled
> l MBM local event is enabled
> tl Both total and local MBM events are enabled
> _ None of the MBM events are enabled
>
> Signed-off-by: Babu Moger <babu.moger@amd.com>
> ---
> v5: Replaced "assignment flags" with "flags".
> Changes related to mon structure.
> Changes related renaming the interface from mbm_assign_control to
> mbm_control.
>
> v4: Added functionality to query domain specific assigment in.
> rdtgroup_abmc_dom_state().
>
> v3: New patch.
> Addresses the feedback to provide the global assignment interface.
> https://lore.kernel.org/lkml/c73f444b-83a1-4e9a-95d3-54c5165ee782@intel.com/
> ---
> Documentation/arch/x86/resctrl.rst | 54 ++++++++++
> arch/x86/kernel/cpu/resctrl/monitor.c | 1 +
> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 130 +++++++++++++++++++++++++
> 3 files changed, 185 insertions(+)
>
> diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
> index 4c41c5622627..05fee779e109 100644
> --- a/Documentation/arch/x86/resctrl.rst
> +++ b/Documentation/arch/x86/resctrl.rst
> @@ -304,6 +304,60 @@ with the following files:
> "num_mbm_cntrs":
> The number of monitoring counters available for assignment.
>
> +"mbm_control":
> + Available when ABMC features are supported.

"Available when ABMC features are supported." can be dropped

> + Reports the resctrl group and monitor status of each group.
> +
> + List follows the following format:
> + "<CTRL_MON group>/<MON group>/<domain_id>=<flags>"
> +
> + Format for specific type of grpups:

grpups -> groups

> +
> + * Default CTRL_MON group:
> + "//<domain_id>=<flags>"
> +
> + * Non-default CTRL_MON group:
> + "<CTRL_MON group>//<domain_id>=<flags>"
> +
> + * Child MON group of default CTRL_MON group:
> + "/<MON group>/<domain_id>=<flags>"
> +
> + * Child MON group of non-default CTRL_MON group:
> + "<CTRL_MON group>/<MON group>/<domain_id>=<flags>"
> +
> + Flags can be one of the following:
> + ::
> +
> + t MBM total event is enabled.
> + l MBM local event is enabled.
> + tl Both total and local MBM events are enabled.
> + _ None of the MBM events are enabled.
> +
> + Examples:
> + ::
> +
> + # mkdir /sys/fs/resctrl/mon_groups/child_default_mon_grp
> + # mkdir /sys/fs/resctrl/non_default_ctrl_mon_grp
> + # mkdir /sys/fs/resctrl/non_default_ctrl_mon_grp/mon_groups/child_non_default_mon_grp
> +
> + # cat /sys/fs/resctrl/info/L3_MON/mbm_control
> + non_default_ctrl_mon_grp//0=tl;1=tl;
> + non_default_ctrl_mon_grp/child_non_default_mon_grp/0=tl;1=tl;
> + //0=tl;1=tl;
> + /child_default_mon_grp/0=tl;1=tl;
> +
> + There are four resctrl groups. All the groups have total and local events are
> + enabled on domain 0 and 1.

"All the groups have total and local events are enabled" -> "All the groups have total and local events enabled"?

> +

The text below seems to repeat ealier description.

> + non_default_ctrl_mon_grp// - This is a non-default CTRL_MON group.
> +
> + non_default_ctrl_mon_grp/child_non_default_mon_grp/ - This is a child monitor
> + group of non-default CTRL_MON group.
> +
> + // - This is a default CTRL_MON group.
> +
> + /child_default_mon_grp/ - This is a child monitor group of default CTRL_MON group.
> +
> "max_threshold_occupancy":
> Read/write file provides the largest value (in
> bytes) at which a previously used LLC_occupancy
> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
> index b96b0a8bd7d3..684730f1a72d 100644
> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> @@ -1244,6 +1244,7 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
> r->mon.num_mbm_cntrs = 64;
>
> resctrl_file_fflags_init("num_mbm_cntrs", RFTYPE_MON_INFO);
> + resctrl_file_fflags_init("mbm_control", RFTYPE_MON_INFO);

Shouldn't this file always be present?

> }
> }
>
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index d978668c8865..0de9f23d5389 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -944,6 +944,130 @@ static ssize_t rdtgroup_mbm_mode_write(struct kernfs_open_file *of,
> return ret ?: nbytes;
> }
>
> +static void rdtgroup_abmc_dom_cfg(void *info)
> +{
> + u64 *msrval = info;
> +
> + wrmsrl(MSR_IA32_L3_QOS_ABMC_CFG, *msrval);
> + rdmsrl(MSR_IA32_L3_QOS_ABMC_DSC, *msrval);
> +}
> +
> +/*
> + * Writing the counter id with CfgEn=0 on L3_QOS_ABMC_CFG and reading
> + * L3_QOS_ABMC_DSC back will return configuration of the counter
> + * specified.

Can this be expanded to explain what the return values mean?

> + */
> +static int rdtgroup_abmc_dom_state(struct rdt_mon_domain *d, u32 cntr_id,
> + u32 rmid)
> +{
> + union l3_qos_abmc_cfg abmc_cfg = { 0 };
> +
> + abmc_cfg.split.cfg_en = 0;
> + abmc_cfg.split.cntr_id = cntr_id;
> +
> + smp_call_function_any(&d->hdr.cpu_mask, rdtgroup_abmc_dom_cfg,
> + &abmc_cfg, 1);
> +
> + if (abmc_cfg.split.cntr_en && abmc_cfg.split.bw_src == rmid)
> + return 0;
> + else
> + return -1;
> +}
> +
> +static char *rdtgroup_mon_state_to_str(struct rdtgroup *rdtgrp,
> + struct rdt_mon_domain *d, char *str)
> +{
> + char *tmp = str;
> + int dom_state = ASSIGN_NONE;

reverse fir

> +
> + /*
> + * Query the monitor state for the domain.
> + * Index 0 for evtid == QOS_L3_MBM_TOTAL_EVENT_ID
> + * Index 1 for evtid == QOS_L3_MBM_LOCAL_EVENT_ID

Why not use the helper?

> + */
> + if (rdtgrp->mon.cntr_id[0] != MON_CNTR_UNSET)
> + if (!rdtgroup_abmc_dom_state(d, rdtgrp->mon.cntr_id[0], rdtgrp->mon.rmid))
> + dom_state |= ASSIGN_TOTAL;
> +
> + if (rdtgrp->mon.cntr_id[1] != MON_CNTR_UNSET)
> + if (!rdtgroup_abmc_dom_state(d, rdtgrp->mon.cntr_id[1], rdtgrp->mon.rmid))
> + dom_state |= ASSIGN_LOCAL;
> +
> + switch (dom_state) {
> + case ASSIGN_NONE:
> + *tmp++ = '_';
> + break;
> + case (ASSIGN_TOTAL | ASSIGN_LOCAL):
> + *tmp++ = 't';
> + *tmp++ = 'l';
> + break;
> + case ASSIGN_TOTAL:
> + *tmp++ = 't';
> + break;
> + case ASSIGN_LOCAL:
> + *tmp++ = 'l';
> + break;
> + default:
> + break;
> + }

This switch statement does not scale. Adding new flags will be painful. Can flags not
just incrementally be printed as learned from hardware with "_" printed as last resort?
This would elimininate need for these "ASSIGN" flags.

> +
> + *tmp = '\0';
> + return str;
> +}
> +
> +static int rdtgroup_mbm_control_show(struct kernfs_open_file *of,
> + struct seq_file *s, void *v)
> +{
> + struct rdt_resource *r = of->kn->parent->priv;
> + struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
> + struct rdt_mon_domain *dom;
> + struct rdtgroup *rdtg;
> + int grp_default = 0;
> + char str[10];
> +
> + if (!hw_res->abmc_enabled) {
> + rdt_last_cmd_puts("ABMC feature is not enabled\n");
> + return -EINVAL;
> + }
> +
> + mutex_lock(&rdtgroup_mutex);
> +
> + list_for_each_entry(rdtg, &rdt_all_groups, rdtgroup_list) {
> + struct rdtgroup *crg;
> +
> + if (rdtg == &rdtgroup_default) {
> + grp_default = 1;
> + seq_puts(s, "//");
> + } else {
> + grp_default = 0;
> + seq_printf(s, "%s//", rdtg->kn->name);
> + }

Isn't the default resource group's name already empty string? That should
eliminate the need for this special handling, no?

> +
> + list_for_each_entry(dom, &r->mon_domains, hdr.list)
> + seq_printf(s, "%d=%s;", dom->hdr.id,
> + rdtgroup_mon_state_to_str(rdtg, dom, str));
> + seq_putc(s, '\n');
> +
> + list_for_each_entry(crg, &rdtg->mon.crdtgrp_list,
> + mon.crdtgrp_list) {
> + if (grp_default)
> + seq_printf(s, "/%s/", crg->kn->name);
> + else
> + seq_printf(s, "%s/%s/", rdtg->kn->name,
> + crg->kn->name);
> +

Same here .... with default group having name of empty string it can just be
printed directly, no?

> + list_for_each_entry(dom, &r->mon_domains, hdr.list)
> + seq_printf(s, "%d=%s;", dom->hdr.id,
> + rdtgroup_mon_state_to_str(crg, dom, str));
> + seq_putc(s, '\n');
> + }
> + }
> +
> + mutex_unlock(&rdtgroup_mutex);
> +
> + return 0;
> +}
> +
> #ifdef CONFIG_PROC_CPU_RESCTRL
>
> /*
> @@ -2156,6 +2280,12 @@ static struct rftype res_common_files[] = {
> .kf_ops = &rdtgroup_kf_single_ops,
> .seq_show = rdtgroup_num_mbm_cntrs_show,
> },
> + {
> + .name = "mbm_control",
> + .mode = 0444,
> + .kf_ops = &rdtgroup_kf_single_ops,
> + .seq_show = rdtgroup_mbm_control_show,
> + },
> {
> .name = "cpus_list",
> .mode = 0644,

Reinette