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x86/intel_rdt/mba_sc: Prepare for feedback loop

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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@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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
This commit is contained in:
Vikas Shivappa 2018-04-20 15:36:20 -07:00 committed by Thomas Gleixner
parent 8205a078ba
commit ba0f26d852
2 changed files with 48 additions and 6 deletions
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10
arch/x86/kernel/cpu/intel_rdt.h
View File

@ -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;
};
/**

44
arch/x86/kernel/cpu/intel_rdt_monitor.c
View File

@ -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.