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Message-ID: <20231025235046.12940-1-tony.luck@intel.com>
Date: Wed, 25 Oct 2023 16:50:46 -0700
From: Tony Luck <tony.luck@...el.com>
To: Fenghua Yu <fenghua.yu@...el.com>,
Reinette Chatre <reinette.chatre@...el.com>,
Peter Newman <peternewman@...gle.com>,
Jonathan Corbet <corbet@....net>,
Shuah Khan <skhan@...uxfoundation.org>, x86@...nel.org
Cc: Shaopeng Tan <tan.shaopeng@...itsu.com>,
James Morse <james.morse@....com>,
Jamie Iles <quic_jiles@...cinc.com>,
Babu Moger <babu.moger@....com>,
Randy Dunlap <rdunlap@...radead.org>,
linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
patches@...ts.linux.dev, Tony Luck <tony.luck@...el.com>
Subject: [PATCH v2] 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.
Signed-off-by: Tony Luck <tony.luck@...el.com>
---
Changes since v1:
+ Both Peter and Babu didn't like my get_mbm_data() function. Peter
thought it just needed a more descriptive name. But Babu explained
how to get rid of it completley. I went with a modified version of
Babu's suggestion (saving the event to use for mba_MBps during
initialization, instead of checking every time).
arch/x86/kernel/cpu/resctrl/monitor.c | 41 ++++++++++++++++----------
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 2 +-
2 files changed, 27 insertions(+), 16 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index f136ac046851..6c3536af024e 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -73,6 +73,13 @@ unsigned int resctrl_rmid_realloc_threshold;
*/
unsigned int resctrl_rmid_realloc_limit;
+/*
+ * MBM monitor event to use for the mba_MBps mount option.
+ * Preference is QOS_L3_MBM_LOCAL_EVENT_ID, but fall
+ * back to QOS_L3_MBM_TOTAL_EVENT_ID.
+ */
+static enum resctrl_event_id mba_mbps_evt_id;
+
#define CF(cf) ((unsigned long)(1048576 * (cf) + 0.5))
/*
@@ -431,7 +438,7 @@ 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_state(rr->d, rmid, mba_mbps_evt_id);
u64 cur_bw, bytes, cur_bytes;
cur_bytes = rr->val;
@@ -526,14 +533,14 @@ 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_state(dom_mbm, rmid, mba_mbps_evt_id);
dom_mba = get_domain_from_cpu(smp_processor_id(), r_mba);
if (!dom_mba) {
@@ -553,7 +560,7 @@ 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_state(dom_mbm, entry->mon.rmid, mba_mbps_evt_id);
cur_bw += cmbm_data->prev_bw;
delta_bw += cmbm_data->delta_bw;
}
@@ -595,7 +602,7 @@ 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_state(dom_mbm, entry->mon.rmid, mba_mbps_evt_id);
cmbm_data->delta_comp = true;
}
}
@@ -621,15 +628,15 @@ 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);
}
/*
@@ -769,10 +776,14 @@ static void l3_mon_evt_init(struct rdt_resource *r)
if (is_llc_occupancy_enabled())
list_add_tail(&llc_occupancy_event.list, &r->evt_list);
- if (is_mbm_total_enabled())
+ if (is_mbm_total_enabled()) {
list_add_tail(&mbm_total_event.list, &r->evt_list);
- if (is_mbm_local_enabled())
+ mba_mbps_evt_id = QOS_L3_MBM_TOTAL_EVENT_ID;
+ }
+ if (is_mbm_local_enabled()) {
list_add_tail(&mbm_local_event.list, &r->evt_list);
+ mba_mbps_evt_id = QOS_L3_MBM_LOCAL_EVENT_ID;
+ }
}
int __init rdt_get_mon_l3_config(struct rdt_resource *r)
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
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