Commit-ID: ba0f26d8529c2dfc9aa6d9e8a338180737f8c1be
Gitweb: https://git.kernel.org/tip/ba0f26d8529c2dfc9aa6d9e8a338180737f8c1be
Author: Vikas Shivappa <vikas.shivappa@xxxxxxxxxxxxxxx>
AuthorDate: Fri, 20 Apr 2018 15:36:20 -0700
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Sat, 19 May 2018 13:16:44 +0200
x86/intel_rdt/mba_sc: Prepare for feedback loop
This is a preparatory patch for the mba feedback loop. Add support to
measure the "bandwidth in MBps" and the "delta bandwidth". Measure it by
reading the MBM IA32_QM_CTR MSRs and calculating the amount of "bytes"
moved. There is no user space interface for this and will only be used by
the feedback loop patch.
Signed-off-by: Vikas Shivappa <vikas.shivappa@xxxxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: ravi.v.shankar@xxxxxxxxx
Cc: tony.luck@xxxxxxxxx
Cc: fenghua.yu@xxxxxxxxx
Cc: vikas.shivappa@xxxxxxxxx
Cc: ak@xxxxxxxxxxxxxxx
Cc: hpa@xxxxxxxxx
Link: https://lkml.kernel.org/r/1524263781-14267-6-git-send-email-vikas.shivappa@xxxxxxxxxxxxxxx
---
arch/x86/kernel/cpu/intel_rdt.h | 10 ++++++++
arch/x86/kernel/cpu/intel_rdt_monitor.c | 44 ++++++++++++++++++++++++++++-----
2 files changed, 48 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kernel/cpu/intel_rdt.h b/arch/x86/kernel/cpu/intel_rdt.h
index 91cc31087e8a..66a0ba37a8a3 100644
--- a/arch/x86/kernel/cpu/intel_rdt.h
+++ b/arch/x86/kernel/cpu/intel_rdt.h
@@ -180,10 +180,20 @@ struct rftype {
* struct mbm_state - status for each MBM counter in each domain
* @chunks: Total data moved (multiply by rdt_group.mon_scale to get bytes)
* @prev_msr Value of IA32_QM_CTR for this RMID last time we read it
+ * @chunks_bw Total local data moved. Used for bandwidth calculation
+ * @prev_bw_msr:Value of previous IA32_QM_CTR for bandwidth counting
+ * @prev_bw The most recent bandwidth in MBps
+ * @delta_bw Difference between the current and previous bandwidth
+ * @delta_comp Indicates whether to compute the delta_bw
*/
struct mbm_state {
u64 chunks;
u64 prev_msr;
+ u64 chunks_bw;
+ u64 prev_bw_msr;
+ u32 prev_bw;
+ u32 delta_bw;
+ bool delta_comp;
};
/**
diff --git a/arch/x86/kernel/cpu/intel_rdt_monitor.c b/arch/x86/kernel/cpu/intel_rdt_monitor.c
index 681450eee428..7690402c42b7 100644
--- a/arch/x86/kernel/cpu/intel_rdt_monitor.c
+++ b/arch/x86/kernel/cpu/intel_rdt_monitor.c
@@ -225,10 +225,18 @@ void free_rmid(u32 rmid)
list_add_tail(&entry->list, &rmid_free_lru);
}
+static u64 mbm_overflow_count(u64 prev_msr, u64 cur_msr)
+{
+ u64 shift = 64 - MBM_CNTR_WIDTH, chunks;
+
+ chunks = (cur_msr << shift) - (prev_msr << shift);
+ return chunks >>= shift;
+}
+
static int __mon_event_count(u32 rmid, struct rmid_read *rr)
{
- u64 chunks, shift, tval;
struct mbm_state *m;
+ u64 chunks, tval;
tval = __rmid_read(rmid, rr->evtid);
if (tval & (RMID_VAL_ERROR | RMID_VAL_UNAVAIL)) {
@@ -254,14 +262,12 @@ static int __mon_event_count(u32 rmid, struct rmid_read *rr)
}
if (rr->first) {
- m->prev_msr = tval;
- m->chunks = 0;
+ memset(m, 0, sizeof(struct mbm_state));
+ m->prev_bw_msr = m->prev_msr = tval;
return 0;
}
- shift = 64 - MBM_CNTR_WIDTH;
- chunks = (tval << shift) - (m->prev_msr << shift);
- chunks >>= shift;
+ chunks = mbm_overflow_count(m->prev_msr, tval);
m->chunks += chunks;
m->prev_msr = tval;
@@ -269,6 +275,32 @@ static int __mon_event_count(u32 rmid, struct rmid_read *rr)
return 0;
}
+/*
+ * Supporting function to calculate the memory bandwidth
+ * and delta bandwidth in MBps.
+ */
+static void mbm_bw_count(u32 rmid, struct rmid_read *rr)
+{
+ struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3];
+ struct mbm_state *m = &rr->d->mbm_local[rmid];
+ u64 tval, cur_bw, chunks;
+
+ tval = __rmid_read(rmid, rr->evtid);
+ if (tval & (RMID_VAL_ERROR | RMID_VAL_UNAVAIL))
+ return;
+
+ chunks = mbm_overflow_count(m->prev_bw_msr, tval);
+ m->chunks_bw += chunks;
+ m->chunks = m->chunks_bw;
+ cur_bw = (chunks * r->mon_scale) >> 20;
+
+ if (m->delta_comp)
+ m->delta_bw = abs(cur_bw - m->prev_bw);
+ m->delta_comp = false;
+ m->prev_bw = cur_bw;
+ m->prev_bw_msr = tval;
+}
+
/*
* This is called via IPI to read the CQM/MBM counters
* on a domain.
--
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