Messages in this thread | | | Date | Tue, 24 Oct 2023 18:20:17 -0500 | Subject | Re: [PATCH] x86/resctrl: mba_MBps: Fall back to total b/w if local b/w unavailable | From | "Moger, Babu" <> |
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Hi Tony,
> -----Original Message----- > From: Tony Luck <tony.luck@intel.com> > Sent: Tuesday, October 24, 2023 1:16 PM > To: Fenghua Yu <fenghua.yu@intel.com>; Reinette Chatre > <reinette.chatre@intel.com>; Peter Newman <peternewman@google.com>; > Jonathan Corbet <corbet@lwn.net>; Shuah Khan <skhan@linuxfoundation.org>; > x86@kernel.org > Cc: Shaopeng Tan <tan.shaopeng@fujitsu.com>; James Morse > <james.morse@arm.com>; Jamie Iles <quic_jiles@quicinc.com>; Moger, Babu > <Babu.Moger@amd.com>; Randy Dunlap <rdunlap@infradead.org>; linux- > kernel@vger.kernel.org; linux-doc@vger.kernel.org; patches@lists.linux.dev; > Tony Luck <tony.luck@intel.com> > Subject: [PATCH] x86/resctrl: mba_MBps: Fall back to total b/w if local b/w > unavailable > > On Intel the various resource director technology (RDT) features are all > orthogonal and independently enumerated. Thus it is possible to have a system > that provides "total" memory bandwidth measurements without providing > "local" bandwidth measurements. > > If local bandwidth measurement is not available, do not give up on providing > the "mba_MBps" feedback option completely, make the code fall back to using > total bandwidth.
Is this customer requirement ? What do you mean by " If local bandwidth measurement is not available" ? Is the hardware supports only total bandwidth and not local?
It can get real ugly if we try to handle one special case.
thanks Babu
> > Signed-off-by: Tony Luck <tony.luck@intel.com> > --- > arch/x86/kernel/cpu/resctrl/monitor.c | 34 ++++++++++++++++---------- > arch/x86/kernel/cpu/resctrl/rdtgroup.c | 2 +- > 2 files changed, 22 insertions(+), 14 deletions(-) > > diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c > b/arch/x86/kernel/cpu/resctrl/monitor.c > index f136ac046851..3b9531cce807 100644 > --- a/arch/x86/kernel/cpu/resctrl/monitor.c > +++ b/arch/x86/kernel/cpu/resctrl/monitor.c > @@ -418,6 +418,14 @@ static int __mon_event_count(u32 rmid, struct > rmid_read *rr) > return 0; > } > > +static struct mbm_state *get_mbm_data(struct rdt_domain *dom_mbm, int > +rmid) { > + if (is_mbm_local_enabled()) > + return &dom_mbm->mbm_local[rmid]; > + > + return &dom_mbm->mbm_total[rmid]; > +} > + > /* > * mbm_bw_count() - Update bw count from values previously read by > * __mon_event_count(). > @@ -431,7 +439,7 @@ static int __mon_event_count(u32 rmid, struct > rmid_read *rr) > */ > static void mbm_bw_count(u32 rmid, struct rmid_read *rr) { > - struct mbm_state *m = &rr->d->mbm_local[rmid]; > + struct mbm_state *m = get_mbm_data(rr->d, rmid); > u64 cur_bw, bytes, cur_bytes; > > cur_bytes = rr->val; > @@ -526,14 +534,14 @@ static void update_mba_bw(struct rdtgroup *rgrp, > struct rdt_domain *dom_mbm) > struct list_head *head; > struct rdtgroup *entry; > > - if (!is_mbm_local_enabled()) > + if (!is_mbm_enabled()) > return; > > r_mba = &rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl; > > closid = rgrp->closid; > rmid = rgrp->mon.rmid; > - pmbm_data = &dom_mbm->mbm_local[rmid]; > + pmbm_data = get_mbm_data(dom_mbm, rmid); > > dom_mba = get_domain_from_cpu(smp_processor_id(), r_mba); > if (!dom_mba) { > @@ -553,7 +561,7 @@ static void update_mba_bw(struct rdtgroup *rgrp, > struct rdt_domain *dom_mbm) > */ > head = &rgrp->mon.crdtgrp_list; > list_for_each_entry(entry, head, mon.crdtgrp_list) { > - cmbm_data = &dom_mbm->mbm_local[entry->mon.rmid]; > + cmbm_data = get_mbm_data(dom_mbm, entry->mon.rmid); > cur_bw += cmbm_data->prev_bw; > delta_bw += cmbm_data->delta_bw; > } > @@ -595,7 +603,7 @@ static void update_mba_bw(struct rdtgroup *rgrp, > struct rdt_domain *dom_mbm) > */ > pmbm_data->delta_comp = true; > list_for_each_entry(entry, head, mon.crdtgrp_list) { > - cmbm_data = &dom_mbm->mbm_local[entry->mon.rmid]; > + cmbm_data = get_mbm_data(dom_mbm, entry->mon.rmid); > cmbm_data->delta_comp = true; > } > } > @@ -621,15 +629,15 @@ static void mbm_update(struct rdt_resource *r, struct > rdt_domain *d, int rmid) > rr.evtid = QOS_L3_MBM_LOCAL_EVENT_ID; > rr.val = 0; > __mon_event_count(rmid, &rr); > - > - /* > - * Call the MBA software controller only for the > - * control groups and when user has enabled > - * the software controller explicitly. > - */ > - if (is_mba_sc(NULL)) > - mbm_bw_count(rmid, &rr); > } > + > + /* > + * Call the MBA software controller only for the > + * control groups and when user has enabled > + * the software controller explicitly. > + */ > + if (is_mba_sc(NULL)) > + mbm_bw_count(rmid, &rr); > } > > /* > diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c > b/arch/x86/kernel/cpu/resctrl/rdtgroup.c > index 69a1de92384a..0c4f8a1b8df0 100644 > --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c > +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c > @@ -2294,7 +2294,7 @@ static bool supports_mba_mbps(void) { > struct rdt_resource *r = > &rdt_resources_all[RDT_RESOURCE_MBA].r_resctrl; > > - return (is_mbm_local_enabled() && > + return (is_mbm_enabled() && > r->alloc_capable && is_mba_linear()); } > > -- > 2.41.0
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