perf_counter: frequency based adaptive irq_period

Instead of specifying the irq_period for a counter, provide a target interrupt
frequency and dynamically adapt the irq_period to match this frequency.

[ Impact: new perf-counter attribute/feature ]

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <20090515132018.646195868@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 8 insertions, 2 deletions

diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index e543ecc129f1..004b6e162b96 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -130,7 +130,11 @@ struct perf_counter_hw_event {
          */
         __u64                   config;
 
-        __u64                   irq_period;
+        union {
+                __u64           irq_period;
+                __u64           irq_freq;
+        };
+
         __u32                   record_type;
         __u32                   read_format;
 
@@ -146,8 +150,9 @@ struct perf_counter_hw_event {
                                 mmap           :  1, /* include mmap data     */
                                 munmap         :  1, /* include munmap data   */
                                 comm           :  1, /* include comm data     */
+                                freq           :  1, /* use freq, not period  */
 
-                                __reserved_1   : 52;
+                                __reserved_1   : 51;
 
         __u32                   extra_config_len;
         __u32                   wakeup_events;  /* wakeup every n events */
@@ -337,6 +342,7 @@ struct hw_perf_counter {
         atomic64_t                      prev_count;
         u64                             irq_period;
         atomic64_t                      period_left;
+        u64                             interrupts;
 #endif
 };