Hi Tony,
-----Original Message-----
From: Tony Luck <tony.luck@xxxxxxxxx>
Sent: Tuesday, October 24, 2023 1:16 PM
To: Fenghua Yu <fenghua.yu@xxxxxxxxx>; Reinette Chatre
<reinette.chatre@xxxxxxxxx>; Peter Newman <peternewman@xxxxxxxxxx>;
Jonathan Corbet <corbet@xxxxxxx>; Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>;
x86@xxxxxxxxxx
Cc: Shaopeng Tan <tan.shaopeng@xxxxxxxxxxx>; James Morse
<james.morse@xxxxxxx>; Jamie Iles <quic_jiles@xxxxxxxxxxx>; Moger, Babu
<Babu.Moger@xxxxxxx>; Randy Dunlap <rdunlap@xxxxxxxxxxxxx>; linux-
kernel@xxxxxxxxxxxxxxx; linux-doc@xxxxxxxxxxxxxxx; patches@xxxxxxxxxxxxxxx;
Tony Luck <tony.luck@xxxxxxxxx>
Subject: [PATCH] x86/resctrl: mba_MBps: Fall back to total b/w if local b/w
unavailable
On Intel the various resource director technology (RDT) features are all
orthogonal and independently enumerated. Thus it is possible to have a system
that provides "total" memory bandwidth measurements without providing
"local" bandwidth measurements.
If local bandwidth measurement is not available, do not give up on providing
the "mba_MBps" feedback option completely, make the code fall back to using
total bandwidth.
Is this customer requirement ?
What do you mean by " If local bandwidth measurement is not available" ?
Is the hardware supports only total bandwidth and not local?
It can get real ugly if we try to handle one special case.
thanks
Babu
Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
---
arch/x86/kernel/cpu/resctrl/monitor.c | 34 ++++++++++++++++----------
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 2 +-
2 files changed, 22 insertions(+), 14 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c
b/arch/x86/kernel/cpu/resctrl/monitor.c
index f136ac046851..3b9531cce807 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -418,6 +418,14 @@ static int __mon_event_count(u32 rmid, struct
rmid_read *rr)
return 0;
}
+static struct mbm_state *get_mbm_data(struct rdt_domain *dom_mbm, int
+rmid) {
+ if (is_mbm_local_enabled())
+ return &dom_mbm->mbm_local[rmid];
+
+ return &dom_mbm->mbm_total[rmid];
+}
+
/*
* mbm_bw_count() - Update bw count from values previously read by
* __mon_event_count().
@@ -431,7 +439,7 @@ static int __mon_event_count(u32 rmid, struct
rmid_read *rr)
*/
static void mbm_bw_count(u32 rmid, struct rmid_read *rr) {
- struct mbm_state *m = &rr->d->mbm_local[rmid];
+ struct mbm_state *m = get_mbm_data(rr->d, rmid);
u64 cur_bw, bytes, cur_bytes;
cur_bytes = rr->val;
@@ -526,14 +534,14 @@ static void update_mba_bw(struct rdtgroup *rgrp,
struct rdt_domain *dom_mbm)
struct list_head *head;
struct rdtgroup *entry;
- if (!is_mbm_local_enabled())
+ if (!is_mbm_enabled())
return;
r_mba = &rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl;
closid = rgrp->closid;
rmid = rgrp->mon.rmid;
- pmbm_data = &dom_mbm->mbm_local[rmid];
+ pmbm_data = get_mbm_data(dom_mbm, rmid);
dom_mba = get_domain_from_cpu(smp_processor_id(), r_mba);
if (!dom_mba) {
@@ -553,7 +561,7 @@ static void update_mba_bw(struct rdtgroup *rgrp,
struct rdt_domain *dom_mbm)
*/
head = &rgrp->mon.crdtgrp_list;
list_for_each_entry(entry, head, mon.crdtgrp_list) {
- cmbm_data = &dom_mbm->mbm_local[entry->mon.rmid];
+ cmbm_data = get_mbm_data(dom_mbm, entry->mon.rmid);
cur_bw += cmbm_data->prev_bw;
delta_bw += cmbm_data->delta_bw;
}
@@ -595,7 +603,7 @@ static void update_mba_bw(struct rdtgroup *rgrp,
struct rdt_domain *dom_mbm)
*/
pmbm_data->delta_comp = true;
list_for_each_entry(entry, head, mon.crdtgrp_list) {
- cmbm_data = &dom_mbm->mbm_local[entry->mon.rmid];
+ cmbm_data = get_mbm_data(dom_mbm, entry->mon.rmid);
cmbm_data->delta_comp = true;
}
}
@@ -621,15 +629,15 @@ static void mbm_update(struct rdt_resource *r, struct
rdt_domain *d, int rmid)
rr.evtid = QOS_L3_MBM_LOCAL_EVENT_ID;
rr.val = 0;
__mon_event_count(rmid, &rr);
-
- /*
- * Call the MBA software controller only for the
- * control groups and when user has enabled
- * the software controller explicitly.
- */
- if (is_mba_sc(NULL))
- mbm_bw_count(rmid, &rr);
}
+
+ /*
+ * Call the MBA software controller only for the
+ * control groups and when user has enabled
+ * the software controller explicitly.
+ */
+ if (is_mba_sc(NULL))
+ mbm_bw_count(rmid, &rr);
}
/*
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 69a1de92384a..0c4f8a1b8df0 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -2294,7 +2294,7 @@ static bool supports_mba_mbps(void) {
struct rdt_resource *r =
&rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl;
- return (is_mbm_local_enabled() &&
+ return (is_mbm_enabled() &&
r->alloc_capable && is_mba_linear()); }
--
2.41.0
