summaryrefslogtreecommitdiffstats
path: root/include/linux/perf_event.h
diff options
context:
space:
mode:
Diffstat (limited to 'include/linux/perf_event.h')
-rw-r--r--include/linux/perf_event.h90
1 files changed, 80 insertions, 10 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index bd9f55a5958..ddbb6a901f6 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -299,18 +299,31 @@ struct perf_event_mmap_page {
/*
* Bits needed to read the hw events in user-space.
*
- * u32 seq;
- * s64 count;
+ * u32 seq, time_mult, time_shift, idx, width;
+ * u64 count, enabled, running;
+ * u64 cyc, time_offset;
+ * s64 pmc = 0;
*
* do {
* seq = pc->lock;
- *
* barrier()
- * if (pc->index) {
- * count = pmc_read(pc->index - 1);
- * count += pc->offset;
- * } else
- * goto regular_read;
+ *
+ * enabled = pc->time_enabled;
+ * running = pc->time_running;
+ *
+ * if (pc->cap_usr_time && enabled != running) {
+ * cyc = rdtsc();
+ * time_offset = pc->time_offset;
+ * time_mult = pc->time_mult;
+ * time_shift = pc->time_shift;
+ * }
+ *
+ * idx = pc->index;
+ * count = pc->offset;
+ * if (pc->cap_usr_rdpmc && idx) {
+ * width = pc->pmc_width;
+ * pmc = rdpmc(idx - 1);
+ * }
*
* barrier();
* } while (pc->lock != seq);
@@ -323,14 +336,57 @@ struct perf_event_mmap_page {
__s64 offset; /* add to hardware event value */
__u64 time_enabled; /* time event active */
__u64 time_running; /* time event on cpu */
- __u32 time_mult, time_shift;
+ union {
+ __u64 capabilities;
+ __u64 cap_usr_time : 1,
+ cap_usr_rdpmc : 1,
+ cap_____res : 62;
+ };
+
+ /*
+ * If cap_usr_rdpmc this field provides the bit-width of the value
+ * read using the rdpmc() or equivalent instruction. This can be used
+ * to sign extend the result like:
+ *
+ * pmc <<= 64 - width;
+ * pmc >>= 64 - width; // signed shift right
+ * count += pmc;
+ */
+ __u16 pmc_width;
+
+ /*
+ * If cap_usr_time the below fields can be used to compute the time
+ * delta since time_enabled (in ns) using rdtsc or similar.
+ *
+ * u64 quot, rem;
+ * u64 delta;
+ *
+ * quot = (cyc >> time_shift);
+ * rem = cyc & ((1 << time_shift) - 1);
+ * delta = time_offset + quot * time_mult +
+ * ((rem * time_mult) >> time_shift);
+ *
+ * Where time_offset,time_mult,time_shift and cyc are read in the
+ * seqcount loop described above. This delta can then be added to
+ * enabled and possible running (if idx), improving the scaling:
+ *
+ * enabled += delta;
+ * if (idx)
+ * running += delta;
+ *
+ * quot = count / running;
+ * rem = count % running;
+ * count = quot * enabled + (rem * enabled) / running;
+ */
+ __u16 time_shift;
+ __u32 time_mult;
__u64 time_offset;
/*
* Hole for extension of the self monitor capabilities
*/
- __u64 __reserved[121]; /* align to 1k */
+ __u64 __reserved[120]; /* align to 1k */
/*
* Control data for the mmap() data buffer.
@@ -550,6 +606,7 @@ struct perf_guest_info_callbacks {
#include <linux/irq_work.h>
#include <linux/static_key.h>
#include <linux/atomic.h>
+#include <linux/sysfs.h>
#include <asm/local.h>
#define PERF_MAX_STACK_DEPTH 255
@@ -1291,5 +1348,18 @@ do { \
register_cpu_notifier(&fn##_nb); \
} while (0)
+
+#define PMU_FORMAT_ATTR(_name, _format) \
+static ssize_t \
+_name##_show(struct device *dev, \
+ struct device_attribute *attr, \
+ char *page) \
+{ \
+ BUILD_BUG_ON(sizeof(_format) >= PAGE_SIZE); \
+ return sprintf(page, _format "\n"); \
+} \
+ \
+static struct device_attribute format_attr_##_name = __ATTR_RO(_name)
+
#endif /* __KERNEL__ */
#endif /* _LINUX_PERF_EVENT_H */