| Message ID | 20230421141723.2405942-7-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: > When RMIDs are soft, __mon_event_count() only needs to report the > current byte count in memory and should not touch the hardware RMIDs. > > Create a parallel version for the soft RMID configuration and update > __mon_event_count() to choose between it and the original depending on > whether the soft RMID static key is enabled. Please note that the changelog refers to "whether the soft RMID static key is enabled" but the patch uses a bool instead of a static key. > > Signed-off-by: Peter Newman <peternewman@google.com> > --- > arch/x86/kernel/cpu/resctrl/monitor.c | 33 ++++++++++++++++++++++++++- > 1 file changed, 32 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c > index bb857eefa3b0..3d54a634471a 100644 > --- a/arch/x86/kernel/cpu/resctrl/monitor.c > +++ b/arch/x86/kernel/cpu/resctrl/monitor.c > @@ -487,7 +487,30 @@ void resctrl_mbm_flush_cpu(void) > __mbm_flush(QOS_L3_MBM_TOTAL_EVENT_ID, r, d); > } > > -static int __mon_event_count(u32 rmid, struct rmid_read *rr) > +static int __mon_event_count_soft_rmid(u32 rmid, struct rmid_read *rr) > +{ > + struct mbm_state *m; > + > + WARN_ON(!is_mbm_event(rr->evtid)); > + m = get_mbm_state(rr->d, rmid, rr->evtid); > + if (!m) > + /* implies !is_mbm_event(...) */ > + return -1; > + > + rr->val += atomic64_read(&m->soft_rmid_bytes); > + > + if (rr->first) { > + /* > + * Discard any bandwidth resulting from the initial HW counter > + * reads. > + */ > + atomic64_set(&m->soft_rmid_bytes, 0); > + } The above is not clear to me. If rr->first is true then it would read soft_rmid_bytes and then immediately reset it? Reinette
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c index bb857eefa3b0..3d54a634471a 100644 --- a/arch/x86/kernel/cpu/resctrl/monitor.c +++ b/arch/x86/kernel/cpu/resctrl/monitor.c @@ -487,7 +487,30 @@ void resctrl_mbm_flush_cpu(void) __mbm_flush(QOS_L3_MBM_TOTAL_EVENT_ID, r, d); } -static int __mon_event_count(u32 rmid, struct rmid_read *rr) +static int __mon_event_count_soft_rmid(u32 rmid, struct rmid_read *rr) +{ + struct mbm_state *m; + + WARN_ON(!is_mbm_event(rr->evtid)); + m = get_mbm_state(rr->d, rmid, rr->evtid); + if (!m) + /* implies !is_mbm_event(...) */ + return -1; + + rr->val += atomic64_read(&m->soft_rmid_bytes); + + if (rr->first) { + /* + * Discard any bandwidth resulting from the initial HW counter + * reads. + */ + atomic64_set(&m->soft_rmid_bytes, 0); + } + + return 0; +} + +static int __mon_event_count_default(u32 rmid, struct rmid_read *rr) { struct mbm_state *m; u64 tval = 0; @@ -509,6 +532,14 @@ static int __mon_event_count(u32 rmid, struct rmid_read *rr) return 0; } +static int __mon_event_count(u32 rmid, struct rmid_read *rr) +{ + if (rdt_mon_soft_rmid) + return __mon_event_count_soft_rmid(rmid, rr); + else + return __mon_event_count_default(rmid, rr); +} + /* * mbm_bw_count() - Update bw count from values previously read by * __mon_event_count().
When RMIDs are soft, __mon_event_count() only needs to report the current byte count in memory and should not touch the hardware RMIDs. Create a parallel version for the soft RMID configuration and update __mon_event_count() to choose between it and the original depending on whether the soft RMID static key is enabled. Signed-off-by: Peter Newman <peternewman@google.com> --- arch/x86/kernel/cpu/resctrl/monitor.c | 33 ++++++++++++++++++++++++++- 1 file changed, 32 insertions(+), 1 deletion(-)