| Message ID | 20230421141723.2405942-6-peternewman@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | x86/resctrl: Use soft RMIDs for reliable MBM on AMD | expand |
Hi Peter, On 4/21/2023 7:17 AM, Peter Newman wrote: > There is no point in using IPIs to call mon_event_count() when it is > only reading software counters from memory. > > When RMIDs are soft, mon_event_read() just calls mon_event_count() > directly. From this patch forward the patch ordering is a bit confusing. At this time mon_event_count() does not read software counters from memory so I think this change should move to later. Also, note that rdt_mon_soft_rmid is introduced here but the reader is left wondering how it is set until the final patch in this series. Reinette
diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c index b44c487727d4..b2ed25a08f6f 100644 --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c @@ -534,7 +534,14 @@ void mon_event_read(struct rmid_read *rr, struct rdt_resource *r, rr->val = 0; rr->first = first; - smp_call_function_any(&d->cpu_mask, mon_event_count, rr, 1); + if (rdt_mon_soft_rmid) + /* + * Soft RMID counters reside in memory, so they can be read from + * anywhere. + */ + mon_event_count(rr); + else + smp_call_function_any(&d->cpu_mask, mon_event_count, rr, 1); } int rdtgroup_mondata_show(struct seq_file *m, void *arg) diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h index 256eee05d447..e6ff31a4dbc4 100644 --- a/arch/x86/kernel/cpu/resctrl/internal.h +++ b/arch/x86/kernel/cpu/resctrl/internal.h @@ -115,6 +115,7 @@ struct rmid_read { extern bool rdt_alloc_capable; extern bool rdt_mon_capable; +extern bool rdt_mon_soft_rmid; extern unsigned int rdt_mon_features; extern struct list_head resctrl_schema_all; diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c index 3671100d3cc7..bb857eefa3b0 100644 --- a/arch/x86/kernel/cpu/resctrl/monitor.c +++ b/arch/x86/kernel/cpu/resctrl/monitor.c @@ -57,6 +57,11 @@ static struct rmid_entry *rmid_ptrs; */ bool rdt_mon_capable; +/* + * Global boolean to indicate when RMIDs are implemented in software. + */ +bool rdt_mon_soft_rmid; + /* * Global to indicate which monitoring events are enabled. */
There is no point in using IPIs to call mon_event_count() when it is only reading software counters from memory. When RMIDs are soft, mon_event_read() just calls mon_event_count() directly. Signed-off-by: Peter Newman <peternewman@google.com> --- arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 9 ++++++++- arch/x86/kernel/cpu/resctrl/internal.h | 1 + arch/x86/kernel/cpu/resctrl/monitor.c | 5 +++++ 3 files changed, 14 insertions(+), 1 deletion(-)