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Message-Id: <8c41a185db1f07dd79a57f5039441ad2c74fcf1b.1585763047.git.reinette.chatre@intel.com>
Date: Wed, 1 Apr 2020 10:51:01 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: tglx@...utronix.de, fenghua.yu@...el.com, bp@...en8.de,
tony.luck@...el.com
Cc: kuo-lang.tseng@...el.com, mingo@...hat.com, babu.moger@....com,
hpa@...or.com, x86@...nel.org, linux-kernel@...r.kernel.org,
Reinette Chatre <reinette.chatre@...el.com>
Subject: [PATCH 1/2] x86/resctrl: Maintain MBM counter width per resource
The original Memory Bandwidth Monitoring (MBM) architectural
definition defines counters of up to 62 bits in the IA32_QM_CTR MSR,
and the first-generation MBM implementation uses 24 bit counters.
Software is required to poll at 1 second or faster to ensure that
data is retrieved before a counter rollover occurs more than once
under worst conditions.
As system bandwidths scale the software requirement is maintained with
the introduction of a per-resource enumerable MBM counter width.
In preparation for supporting hardware with an enumerable MBM counter
width the current globally static MBM counter width is moved to a
per-resource MBM counter width. Currently initialized to 24 always
to result in no functional change.
In essence there is one function, mbm_overflow_count() that needs to
know the counter width to handle rollovers. The static value
used within mbm_overflow_count() will be replaced with a value
discovered from the hardware. Support for learning the MBM counter
width from hardware is added in the change that follows.
Signed-off-by: Reinette Chatre <reinette.chatre@...el.com>
---
arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 8 +++++---
arch/x86/kernel/cpu/resctrl/internal.h | 7 +++++--
arch/x86/kernel/cpu/resctrl/monitor.c | 21 +++++++++++++--------
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 2 +-
4 files changed, 24 insertions(+), 14 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
index 055c8613b531..934c8fb8a64a 100644
--- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
+++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
@@ -495,14 +495,16 @@ int rdtgroup_schemata_show(struct kernfs_open_file *of,
return ret;
}
-void mon_event_read(struct rmid_read *rr, struct rdt_domain *d,
- struct rdtgroup *rdtgrp, int evtid, int first)
+void mon_event_read(struct rmid_read *rr, struct rdt_resource *r,
+ struct rdt_domain *d, struct rdtgroup *rdtgrp,
+ int evtid, int first)
{
/*
* setup the parameters to send to the IPI to read the data.
*/
rr->rgrp = rdtgrp;
rr->evtid = evtid;
+ rr->r = r;
rr->d = d;
rr->val = 0;
rr->first = first;
@@ -539,7 +541,7 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)
goto out;
}
- mon_event_read(&rr, d, rdtgrp, evtid, false);
+ mon_event_read(&rr, r, d, rdtgrp, evtid, false);
if (rr.val & RMID_VAL_ERROR)
seq_puts(m, "Error\n");
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 181c992f448c..28947c790faa 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -87,6 +87,7 @@ union mon_data_bits {
struct rmid_read {
struct rdtgroup *rgrp;
+ struct rdt_resource *r;
struct rdt_domain *d;
int evtid;
bool first;
@@ -460,6 +461,7 @@ struct rdt_resource {
struct list_head evt_list;
int num_rmid;
unsigned int mon_scale;
+ unsigned int mbm_width;
unsigned long fflags;
};
@@ -587,8 +589,9 @@ void rmdir_mondata_subdir_allrdtgrp(struct rdt_resource *r,
unsigned int dom_id);
void mkdir_mondata_subdir_allrdtgrp(struct rdt_resource *r,
struct rdt_domain *d);
-void mon_event_read(struct rmid_read *rr, struct rdt_domain *d,
- struct rdtgroup *rdtgrp, int evtid, int first);
+void mon_event_read(struct rmid_read *rr, struct rdt_resource *r,
+ struct rdt_domain *d, struct rdtgroup *rdtgrp,
+ int evtid, int first);
void mbm_setup_overflow_handler(struct rdt_domain *dom,
unsigned long delay_ms);
void mbm_handle_overflow(struct work_struct *work);
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 773124b0e18a..df964c03f6c6 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -214,9 +214,9 @@ void free_rmid(u32 rmid)
list_add_tail(&entry->list, &rmid_free_lru);
}
-static u64 mbm_overflow_count(u64 prev_msr, u64 cur_msr)
+static u64 mbm_overflow_count(u64 prev_msr, u64 cur_msr, unsigned int width)
{
- u64 shift = 64 - MBM_CNTR_WIDTH, chunks;
+ u64 shift = 64 - width, chunks;
chunks = (cur_msr << shift) - (prev_msr << shift);
return chunks >>= shift;
@@ -256,7 +256,7 @@ static int __mon_event_count(u32 rmid, struct rmid_read *rr)
return 0;
}
- chunks = mbm_overflow_count(m->prev_msr, tval);
+ chunks = mbm_overflow_count(m->prev_msr, tval, rr->r->mbm_width);
m->chunks += chunks;
m->prev_msr = tval;
@@ -278,7 +278,7 @@ static void mbm_bw_count(u32 rmid, struct rmid_read *rr)
if (tval & (RMID_VAL_ERROR | RMID_VAL_UNAVAIL))
return;
- chunks = mbm_overflow_count(m->prev_bw_msr, tval);
+ chunks = mbm_overflow_count(m->prev_bw_msr, tval, rr->r->mbm_width);
m->chunks_bw += chunks;
m->chunks = m->chunks_bw;
cur_bw = (chunks * r->mon_scale) >> 20;
@@ -433,11 +433,12 @@ static void update_mba_bw(struct rdtgroup *rgrp, struct rdt_domain *dom_mbm)
}
}
-static void mbm_update(struct rdt_domain *d, int rmid)
+static void mbm_update(struct rdt_resource *r, struct rdt_domain *d, int rmid)
{
struct rmid_read rr;
rr.first = false;
+ rr.r = r;
rr.d = d;
/*
@@ -510,6 +511,7 @@ void mbm_handle_overflow(struct work_struct *work)
struct rdtgroup *prgrp, *crgrp;
int cpu = smp_processor_id();
struct list_head *head;
+ struct rdt_resource *r;
struct rdt_domain *d;
mutex_lock(&rdtgroup_mutex);
@@ -517,16 +519,18 @@ void mbm_handle_overflow(struct work_struct *work)
if (!static_branch_likely(&rdt_mon_enable_key))
goto out_unlock;
- d = get_domain_from_cpu(cpu, &rdt_resources_all[RDT_RESOURCE_L3]);
+ r = &rdt_resources_all[RDT_RESOURCE_L3];
+
+ d = get_domain_from_cpu(cpu, r);
if (!d)
goto out_unlock;
list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
- mbm_update(d, prgrp->mon.rmid);
+ mbm_update(r, d, prgrp->mon.rmid);
head = &prgrp->mon.crdtgrp_list;
list_for_each_entry(crgrp, head, mon.crdtgrp_list)
- mbm_update(d, crgrp->mon.rmid);
+ mbm_update(r, d, crgrp->mon.rmid);
if (is_mba_sc(NULL))
update_mba_bw(prgrp, d);
@@ -619,6 +623,7 @@ int rdt_get_mon_l3_config(struct rdt_resource *r)
r->mon_scale = boot_cpu_data.x86_cache_occ_scale;
r->num_rmid = boot_cpu_data.x86_cache_max_rmid + 1;
+ r->mbm_width = MBM_CNTR_WIDTH;
/*
* A reasonable upper limit on the max threshold is the number
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 9d4e73a9b5a9..210a6fd375bd 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -2459,7 +2459,7 @@ static int mkdir_mondata_subdir(struct kernfs_node *parent_kn,
goto out_destroy;
if (is_mbm_event(mevt->evtid))
- mon_event_read(&rr, d, prgrp, mevt->evtid, true);
+ mon_event_read(&rr, r, d, prgrp, mevt->evtid, true);
}
kernfs_activate(kn);
return 0;
--
2.21.0
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