From: Vikas Shivappa <vikas.shivappa@linux.intel.com>
To: vikas.shivappa@intel.com, tony.luck@intel.com,
ravi.v.shankar@intel.com, fenghua.yu@intel.com, x86@kernel.org,
tglx@linutronix.de, hpa@zytor.com
Cc: linux-kernel@vger.kernel.org, ak@linux.intel.com,
vikas.shivappa@linux.intel.com
Subject: [PATCH 5/6] x86/intel_rdt/mba_sc: Prepare for feedback loop
Date: Fri, 20 Apr 2018 15:36:20 -0700 [thread overview]
Message-ID: <1524263781-14267-6-git-send-email-vikas.shivappa@linux.intel.com> (raw)
In-Reply-To: <1524263781-14267-1-git-send-email-vikas.shivappa@linux.intel.com>
This is a preparatory patch for the mba feedback loop. We add support to
measure the "bandwidth in MBps" and the "delta bandwidth". We measure it
reading the MBM IA32_QM_CTR MSRs and calculating the amount of "bytes"
moved. There is no user interface for this and will only be used by the
feedback loop patch.
Signed-off-by: Vikas Shivappa <vikas.shivappa@linux.intel.com>
---
arch/x86/kernel/cpu/intel_rdt.h | 10 ++++++++
arch/x86/kernel/cpu/intel_rdt_monitor.c | 45 ++++++++++++++++++++++++++++-----
2 files changed, 49 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kernel/cpu/intel_rdt.h b/arch/x86/kernel/cpu/intel_rdt.h
index 91cc310..66a0ba3 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 681450e..32c9e55 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;
@@ -270,6 +276,33 @@ static int __mon_event_count(u32 rmid, struct rmid_read *rr)
}
/*
+ * 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.
*/
--
1.9.1
next prev parent reply other threads:[~2018-04-20 22:39 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-20 22:36 [PATCH V2 0/6] Memory bandwidth allocation software controller(mba_sc) Vikas Shivappa
2018-04-20 22:36 ` [PATCH 1/6] x86/intel_rdt/mba_sc: Documentation for MBA " Vikas Shivappa
2018-05-19 11:21 ` [tip:x86/cache] " tip-bot for Vikas Shivappa
2018-04-20 22:36 ` [PATCH 2/6] x86/intel_rdt/mba_sc: Enable/disable MBA software controller Vikas Shivappa
2018-05-13 19:35 ` Thomas Gleixner
2018-05-15 20:06 ` Shivappa Vikas
2018-05-19 11:22 ` [tip:x86/cache] " tip-bot for Vikas Shivappa
2018-04-20 22:36 ` [PATCH 3/6] x86/intel_rdt/mba_sc: Add initialization support Vikas Shivappa
2018-05-19 11:22 ` [tip:x86/cache] " tip-bot for Vikas Shivappa
2018-04-20 22:36 ` [PATCH 4/6] x86/intel_rdt/mba_sc: Add schemata support Vikas Shivappa
2018-05-19 11:23 ` [tip:x86/cache] " tip-bot for Vikas Shivappa
2018-04-20 22:36 ` Vikas Shivappa [this message]
2018-05-19 11:23 ` [tip:x86/cache] x86/intel_rdt/mba_sc: Prepare for feedback loop tip-bot for Vikas Shivappa
2018-04-20 22:36 ` [PATCH 6/6] x86/intel_rdt/mba_sc: Feedback loop to dynamically update mem bandwidth Vikas Shivappa
2018-05-19 11:24 ` [tip:x86/cache] " tip-bot for Vikas Shivappa
2018-05-01 0:38 ` [PATCH V2 0/6] Memory bandwidth allocation software controller(mba_sc) Shivappa Vikas
2018-05-02 8:24 ` Thomas Gleixner
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