[PATCH 11/15] perf_counter: re-arrange the perf_event_type

From: Peter Zijlstra
Date: Mon Mar 30 2009 - 13:12:48 EST


Breaks ABI yet again :-)

Change the event type so that [0, 2^31-1] are regular event types, but
[2^31, 2^32-1] forms a bitmask for overflow events.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
---
include/linux/perf_counter.h | 6 +++-
kernel/perf_counter.c | 56 +++++++++++++++++++------------------------
2 files changed, 29 insertions(+), 33 deletions(-)

Index: linux-2.6/include/linux/perf_counter.h
===================================================================
--- linux-2.6.orig/include/linux/perf_counter.h
+++ linux-2.6/include/linux/perf_counter.h
@@ -210,13 +210,15 @@ struct perf_event_header {
};

enum perf_event_type {
- PERF_EVENT_IP = 0,
+
PERF_EVENT_GROUP = 1,

PERF_EVENT_MMAP = 2,
PERF_EVENT_MUNMAP = 3,

- __PERF_EVENT_TID = 0x100,
+ PERF_EVENT_OVERFLOW = 1UL << 31,
+ __PERF_EVENT_IP = 1UL << 30,
+ __PERF_EVENT_TID = 1UL << 29,
};

#ifdef __KERNEL__
Index: linux-2.6/kernel/perf_counter.c
===================================================================
--- linux-2.6.orig/kernel/perf_counter.c
+++ linux-2.6/kernel/perf_counter.c
@@ -1754,50 +1754,44 @@ static void perf_output_end(struct perf_
rcu_read_unlock();
}

-static int perf_output_write(struct perf_counter *counter, int nmi,
- void *buf, ssize_t size)
-{
- struct perf_output_handle handle;
- int ret;
-
- ret = perf_output_begin(&handle, counter, size, nmi);
- if (ret)
- goto out;
-
- perf_output_copy(&handle, buf, size);
- perf_output_end(&handle);
-
-out:
- return ret;
-}
-
static void perf_output_simple(struct perf_counter *counter,
int nmi, struct pt_regs *regs)
{
- unsigned int size;
+ int ret;
+ struct perf_output_handle handle;
+ struct perf_event_header header;
+ u64 ip;
struct {
- struct perf_event_header header;
- u64 ip;
u32 pid, tid;
- } event;
+ } tid_entry;

- event.header.type = PERF_EVENT_IP;
- event.ip = instruction_pointer(regs);
+ header.type = PERF_EVENT_OVERFLOW;
+ header.size = sizeof(header);

- size = sizeof(event);
+ ip = instruction_pointer(regs);
+ header.type |= __PERF_EVENT_IP;
+ header.size += sizeof(ip);

if (counter->hw_event.include_tid) {
/* namespace issues */
- event.pid = current->group_leader->pid;
- event.tid = current->pid;
+ tid_entry.pid = current->group_leader->pid;
+ tid_entry.tid = current->pid;

- event.header.type |= __PERF_EVENT_TID;
- } else
- size -= sizeof(u64);
+ header.type |= __PERF_EVENT_TID;
+ header.size += sizeof(tid_entry);
+ }

- event.header.size = size;
+ ret = perf_output_begin(&handle, counter, header.size, nmi);
+ if (ret)
+ return;
+
+ perf_output_put(&handle, header);
+ perf_output_put(&handle, ip);
+
+ if (counter->hw_event.include_tid)
+ perf_output_put(&handle, tid_entry);

- perf_output_write(counter, nmi, &event, size);
+ perf_output_end(&handle);
}

static void perf_output_group(struct perf_counter *counter, int nmi)

--

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