Hi Babu,
On 9/4/24 3:21 PM, Babu Moger wrote:
> In mbm_cntr_assign mode, the hardware counter should be assigned to read
> the MBM events.
>
> Report "Unassigned" in case the user attempts to read the events without
> assigning the counter.
>
> Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
> ---
> v7: Moved the documentation under "mon_data".
> Updated the text little bit.
>
> v6: Added more explaination in the resctrl.rst
> Added checks to detect "Unassigned" before reading RMID.
>
> v5: New patch.
> ---
> Documentation/arch/x86/resctrl.rst | 10 ++++++++++
> arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 13 ++++++++++++-
> 2 files changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
> index 3e9302971faf..ff5397d19704 100644
> --- a/Documentation/arch/x86/resctrl.rst
> +++ b/Documentation/arch/x86/resctrl.rst
> @@ -417,6 +417,16 @@ When monitoring is enabled all MON groups will also contain:
> for the L3 cache they occupy). These are named "mon_sub_L3_YY"
> where "YY" is the node number.
>
> + The mbm_cntr_assign mode allows users to assign a hardware counter
> + to an RMID-event pair, enabling bandwidth monitoring for as long
> + as the counter remains assigned. The hardware will continue tracking
> + the assigned RMID until the user manually unassigns it, ensuring
> + that counters are not reset during this period. With a limited number
> + of counters, the system may run out of assignable resources. In
> + mbm_cntr_assign mode, MBM event counters will return "Unassigned"
> + if the counter is not allocated to the event when read. Users must
> + manually assign a counter to read the events.
> +
Please consider how this text could also be relevant to soft-ABMC.
> "mon_hw_id":
> Available only with debug option. The identifier used by hardware
> for the monitor group. On x86 this is the RMID.
> diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> index 50fa1fe9a073..fc19b1d131b2 100644
> --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> @@ -562,7 +562,7 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
> struct rdtgroup *rdtgrp;
> struct rdt_resource *r;
> union mon_data_bits md;
> - int ret = 0;
> + int ret = 0, index;
>
> rdtgrp = rdtgroup_kn_lock_live(of->kn);
> if (!rdtgrp) {
> @@ -576,6 +576,15 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
> evtid = md.u.evtid;
> r = &rdt_resources_all[resid].r_resctrl;
>
> + if (resctrl_arch_mbm_cntr_assign_enabled(r) && evtid != QOS_L3_OCCUP_EVENT_ID) {
> + index = mon_event_config_index_get(evtid);
This should use MBM_EVENT_ARRAY_INDEX, not the arch index.
> + if (index != INVALID_CONFIG_INDEX &&
> + rdtgrp->mon.cntr_id[index] == MON_CNTR_UNSET) {
> + rr.err = -ENOENT;
> + goto checkresult;
> + }
> + }
> +
> if (md.u.sum) {
> /*
> * This file requires summing across all domains that share
> @@ -613,6 +622,8 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
> seq_puts(m, "Error\n");
> else if (rr.err == -EINVAL)
> seq_puts(m, "Unavailable\n");
> + else if (rr.err == -ENOENT)
> + seq_puts(m, "Unassigned\n");
> else
> seq_printf(m, "%llu\n", rr.val);
>
Reinette
