perf_counter: add PERF_RECORD_CPU

Allow recording the CPU number the event was generated on.

RFC: this leaves a u32 as reserved, should we fill in the
     node_id() there, or leave this open for future extention,
     as userspace can already easily do the cpu->node mapping
     if needed.

[ Impact: extend perfcounter output record format ]

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090508170029.008627711@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 15 insertions, 0 deletions

diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 0e6303d36c66..614f921d616a 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -105,6 +105,7 @@ enum perf_counter_record_format {
         PERF_RECORD_GROUP       = 1U << 4,
         PERF_RECORD_CALLCHAIN   = 1U << 5,
         PERF_RECORD_CONFIG      = 1U << 6,
+        PERF_RECORD_CPU         = 1U << 7,
 };
 
 /*
@@ -260,6 +261,7 @@ enum perf_event_type {
          *      { u64                   time;     } && PERF_RECORD_TIME
          *      { u64                   addr;     } && PERF_RECORD_ADDR
          *      { u64                   config;   } && PERF_RECORD_CONFIG
+         *      { u32                   cpu, res; } && PERF_RECORD_CPU
          *
          *      { u64                   nr;
          *        { u64 event, val; }   cnt[nr];  } && PERF_RECORD_GROUP
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index c615f52aa408..d850a1fb8d4c 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -1956,6 +1956,9 @@ static void perf_counter_output(struct perf_counter *counter,
         struct perf_callchain_entry *callchain = NULL;
         int callchain_size = 0;
         u64 time;
+        struct {
+                u32 cpu, reserved;
+        } cpu_entry;
 
         header.type = 0;
         header.size = sizeof(header);
@@ -1999,6 +2002,13 @@ static void perf_counter_output(struct perf_counter *counter,
                 header.size += sizeof(u64);
         }
 
+        if (record_type & PERF_RECORD_CPU) {
+                header.type |= PERF_RECORD_CPU;
+                header.size += sizeof(cpu_entry);
+
+                cpu_entry.cpu = raw_smp_processor_id();
+        }
+
         if (record_type & PERF_RECORD_GROUP) {
                 header.type |= PERF_RECORD_GROUP;
                 header.size += sizeof(u64) +
@@ -2037,6 +2047,9 @@ static void perf_counter_output(struct perf_counter *counter,
         if (record_type & PERF_RECORD_CONFIG)
                 perf_output_put(&handle, counter->hw_event.config);
 
+        if (record_type & PERF_RECORD_CPU)
+                perf_output_put(&handle, cpu_entry);
+
         /*
          * XXX PERF_RECORD_GROUP vs inherited counters seems difficult.
          */