[PATCH v20 14/18] x86/resctrl: Fill out rmid_read structure for smp_call*() to read a counter

Tony Luck
2024-06-10T18:35:49Z

mon_event_read() fills out most fields of the struct rmid_read that is
passed via an smp_call*() function to a CPU that is part of the correct
domain to read the monitor counters.

With Sub-NUMA Cluster (SNC) mode there are now two cases to handle:

1) Reading a file that returns a value for a single domain.
+ Choose the CPU to execute from the domain cpu_mask

2) Reading a file that must sum across domains sharing an L3 cache
instance.
+ Indicate to called code that a sum is needed by passing a NULL
rdt_mon_domain pointer.
+ Choose the CPU from the L3 shared_cpu_map.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
arch/x86/kernel/cpu/resctrl/internal.h | 2 +-
arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 39 ++++++++++++++++++-----
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 2 +-
3 files changed, 33 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 77da29ced7eb..75bb1afc4842 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -627,7 +627,7 @@ 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,
struct rdt_mon_domain *d, struct rdtgroup *rdtgrp,
- int evtid, int first);
+ cpumask_t *cpumask, int evtid, int first);
void mbm_setup_overflow_handler(struct rdt_mon_domain *dom,
unsigned long delay_ms,
int exclude_cpu);
diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
index 3b9383612c35..5a43931fd423 100644
--- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
+++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
@@ -515,7 +515,7 @@ static int smp_mon_event_count(void *arg)

void mon_event_read(struct rmid_read *rr, struct rdt_resource *r,
struct rdt_mon_domain *d, struct rdtgroup *rdtgrp,
- int evtid, int first)
+ cpumask_t *cpumask, int evtid, int first)
{
int cpu;

@@ -537,7 +537,7 @@ void mon_event_read(struct rmid_read *rr, struct rdt_resource *r,
return;
}

- cpu = cpumask_any_housekeeping(&d->hdr.cpu_mask, RESCTRL_PICK_ANY_CPU);
+ cpu = cpumask_any_housekeeping(cpumask, RESCTRL_PICK_ANY_CPU);

/*
* cpumask_any_housekeeping() prefers housekeeping CPUs, but
@@ -546,7 +546,7 @@ void mon_event_read(struct rmid_read *rr, struct rdt_resource *r,
* counters on some platforms if its called in IRQ context.
*/
if (tick_nohz_full_cpu(cpu))
- smp_call_function_any(&d->hdr.cpu_mask, mon_event_count, rr, 1);
+ smp_call_function_any(cpumask, mon_event_count, rr, 1);
else
smp_call_on_cpu(cpu, smp_mon_event_count, rr, false);

@@ -575,16 +575,39 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
resid = md.u.rid;
domid = md.u.domid;
evtid = md.u.evtid;
-
r = &rdt_resources_all[resid].r_resctrl;
- hdr = rdt_find_domain(&r->mon_domains, domid, NULL);
- if (!hdr || WARN_ON_ONCE(hdr->type != RESCTRL_MON_DOMAIN)) {
+
+ if (md.u.sum) {
+ /*
+ * This file requires summing across all SNC domains that share
+ * the L3 cache id that was provided in the "domid" field of the
+ * mon_data_bits union. Search all domains in the resource for
+ * one that matches this cache id.
+ */
+ list_for_each_entry(d, &r->mon_domains, hdr.list) {
+ if (d->ci->id == domid) {
+ rr.ci = d->ci;
+ mon_event_read(&rr, r, NULL, rdtgrp, &d->ci->shared_cpu_map, evtid, false);
+ goto checkresult;
+ }
+ }
ret = -ENOENT;
goto out;
+ } else {
+ /*
+ * This file provides data from a single domain. Search
+ * the resource to find the domain with "domid".
+ */
+ hdr = rdt_find_domain(&r->mon_domains, domid, NULL);
+ if (!hdr || WARN_ON_ONCE(hdr->type != RESCTRL_MON_DOMAIN)) {
+ ret = -ENOENT;
+ goto out;
+ }
+ d = container_of(hdr, struct rdt_mon_domain, hdr);
+ mon_event_read(&rr, r, d, rdtgrp, &d->hdr.cpu_mask, evtid, false);
}
- d = container_of(hdr, struct rdt_mon_domain, hdr);

- mon_event_read(&rr, r, d, rdtgrp, evtid, false);
+checkresult:

if (rr.err == -EIO)
seq_puts(m, "Error\n");
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 5142ce43ac13..cd54ca6cc563 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -3070,7 +3070,7 @@ static int mon_add_all_files(struct kernfs_node *kn, struct rdt_mon_domain *d,
return ret;

if (!do_sum && is_mbm_event(mevt->evtid))
- mon_event_read(&rr, r, d, prgrp, mevt->evtid, true);
+ mon_event_read(&rr, r, d, prgrp, &d->hdr.cpu_mask, mevt->evtid, true);
}

return 0;
--
2.45.0