diff options
Diffstat (limited to 'arch/x86/kernel/cpu/perf_event.h')
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event.h | 30 |
1 files changed, 28 insertions, 2 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h index b9698d40ac4b..51a985cbc12f 100644 --- a/arch/x86/kernel/cpu/perf_event.h +++ b/arch/x86/kernel/cpu/perf_event.h @@ -45,6 +45,7 @@ struct event_constraint { u64 code; u64 cmask; int weight; + int overlap; }; struct amd_nb { @@ -151,15 +152,40 @@ struct cpu_hw_events { void *kfree_on_online; }; -#define __EVENT_CONSTRAINT(c, n, m, w) {\ +#define __EVENT_CONSTRAINT(c, n, m, w, o) {\ { .idxmsk64 = (n) }, \ .code = (c), \ .cmask = (m), \ .weight = (w), \ + .overlap = (o), \ } #define EVENT_CONSTRAINT(c, n, m) \ - __EVENT_CONSTRAINT(c, n, m, HWEIGHT(n)) + __EVENT_CONSTRAINT(c, n, m, HWEIGHT(n), 0) + +/* + * The overlap flag marks event constraints with overlapping counter + * masks. This is the case if the counter mask of such an event is not + * a subset of any other counter mask of a constraint with an equal or + * higher weight, e.g.: + * + * c_overlaps = EVENT_CONSTRAINT_OVERLAP(0, 0x09, 0); + * c_another1 = EVENT_CONSTRAINT(0, 0x07, 0); + * c_another2 = EVENT_CONSTRAINT(0, 0x38, 0); + * + * The event scheduler may not select the correct counter in the first + * cycle because it needs to know which subsequent events will be + * scheduled. It may fail to schedule the events then. So we set the + * overlap flag for such constraints to give the scheduler a hint which + * events to select for counter rescheduling. + * + * Care must be taken as the rescheduling algorithm is O(n!) which + * will increase scheduling cycles for an over-commited system + * dramatically. The number of such EVENT_CONSTRAINT_OVERLAP() macros + * and its counter masks must be kept at a minimum. + */ +#define EVENT_CONSTRAINT_OVERLAP(c, n, m) \ + __EVENT_CONSTRAINT(c, n, m, HWEIGHT(n), 1) /* * Constraint on the Event code. |