The flag PERF_X86_EVENT_COMMITTED is used to find uncommitted events for which to call put_event_constraint() when scheduling fails.
These are the newly added events to the list, and must form, per definition, the tail of cpuc->event_list[]. By computing the list index of the last successfull schedule, then iteration can start there and the flag is redundant. There are only 3 callers of x86_schedule_events(), notably: - x86_pmu_add() - x86_pmu_commit_txn() - validate_group() For x86_pmu_add(), cpuc->n_events isn't updated until after schedule_events() succeeds, therefore cpuc->n_events points to the desired index. For x86_pmu_commit_txn(), cpuc->n_events is updated, but we can trivially compute the desired value with cpuc->n_txn -- the number of events added in this transaction. For validate_group(), we can make the rule for x86_pmu_add() work by simply setting cpuc->n_events to 0 before calling schedule_events(). Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> --- arch/x86/events/core.c | 21 ++++++--------------- arch/x86/events/perf_event.h | 1 - 2 files changed, 6 insertions(+), 16 deletions(-) --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -925,19 +925,16 @@ int x86_schedule_events(struct cpu_hw_ev if (!unsched && assign) { for (i = 0; i < n; i++) { e = cpuc->event_list[i]; - e->hw.flags |= PERF_X86_EVENT_COMMITTED; if (x86_pmu.commit_scheduling) x86_pmu.commit_scheduling(cpuc, i, assign[i]); } } else { - for (i = 0; i < n; i++) { + i = cpuc->n_events; + if (cpuc->txn_flags & PERF_PMU_TXN_ADD) + i -= cpuc->n_txn; + + for (; i < n; i++) { e = cpuc->event_list[i]; - /* - * do not put_constraint() on comitted events, - * because they are good to go - */ - if ((e->hw.flags & PERF_X86_EVENT_COMMITTED)) - continue; /* * release events that failed scheduling @@ -1372,11 +1369,6 @@ static void x86_pmu_del(struct perf_even int i; /* - * event is descheduled - */ - event->hw.flags &= ~PERF_X86_EVENT_COMMITTED; - - /* * If we're called during a txn, we only need to undo x86_pmu.add. * The events never got scheduled and ->cancel_txn will truncate * the event_list. @@ -2079,8 +2071,7 @@ static int validate_group(struct perf_ev if (n < 0) goto out; - fake_cpuc->n_events = n; - + fake_cpuc->n_events = 0; ret = x86_pmu.schedule_events(fake_cpuc, n, NULL); out: --- a/arch/x86/events/perf_event.h +++ b/arch/x86/events/perf_event.h @@ -61,7 +61,6 @@ struct event_constraint { #define PERF_X86_EVENT_PEBS_LDLAT 0x0001 /* ld+ldlat data address sampling */ #define PERF_X86_EVENT_PEBS_ST 0x0002 /* st data address sampling */ #define PERF_X86_EVENT_PEBS_ST_HSW 0x0004 /* haswell style datala, store */ -#define PERF_X86_EVENT_COMMITTED 0x0008 /* event passed commit_txn */ #define PERF_X86_EVENT_PEBS_LD_HSW 0x0010 /* haswell style datala, load */ #define PERF_X86_EVENT_PEBS_NA_HSW 0x0020 /* haswell style datala, unknown */ #define PERF_X86_EVENT_EXCL 0x0040 /* HT exclusivity on counter */