From ba0f26d8529c2dfc9aa6d9e8a338180737f8c1be Mon Sep 17 00:00:00 2001 From: Vikas Shivappa Date: Fri, 20 Apr 2018 15:36:20 -0700 Subject: [PATCH] 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 Signed-off-by: Thomas Gleixner Cc: ravi.v.shankar@intel.com Cc: tony.luck@intel.com Cc: fenghua.yu@intel.com Cc: vikas.shivappa@intel.com Cc: ak@linux.intel.com Cc: hpa@zytor.com Link: https://lkml.kernel.org/r/1524263781-14267-6-git-send-email-vikas.shivappa@linux.intel.com --- 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. -- 2.25.1