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authorFrederic Weisbecker <fweisbec@gmail.com>2009-08-10 16:11:32 +0200
committerIngo Molnar <mingo@elte.hu>2009-08-10 16:18:50 +0200
commit304703aba31a87903b8c0db8f5e6890cac2d596d (patch)
treebd233c6fd72d1d674c4a9537cfd6519069914d74
parenta4e95fc2cbb31d70a65beffeaf8773f881328c34 (diff)
downloadconfigs-304703aba31a87903b8c0db8f5e6890cac2d596d.tar.gz
perf_counter: Subtract the buffer size field from the event record size
We compute the perf raw sample size by aligning the raw ftrace event size plus the buffer size field itself. We do that instead of aligning only the perf raw sample size, so that we might economize some in some cases. But this buffer size field is not stored in the perf raw sample, we must then substract its size from the buffer once we computed the alignment unless we may get a useless u32 field in the buffer. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul Mackerras <paulus@samba.org> LKML-Reference: <20090810141129.GA5124@nowhere> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--include/trace/ftrace.h8
1 files changed, 7 insertions, 1 deletions
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 7167b9b97da..a05524fa245 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -637,7 +637,12 @@ __attribute__((section("_ftrace_events"))) event_##call = { \
* pc = preempt_count();
*
* __data_size = ftrace_get_offsets_<call>(&__data_offsets, args);
- * __entry_size = __data_size + sizeof(*entry);
+ *
+ * // Below we want to get the aligned size by taking into account
+ * // the u32 field that will later store the buffer size
+ * __entry_size = ALIGN(__data_size + sizeof(*entry) + sizeof(u32),
+ * sizeof(u64));
+ * __entry_size -= sizeof(u32);
*
* do {
* char raw_data[__entry_size]; <- allocate our sample in the stack
@@ -687,6 +692,7 @@ static void ftrace_profile_##call(proto) \
__data_size = ftrace_get_offsets_##call(&__data_offsets, args); \
__entry_size = ALIGN(__data_size + sizeof(*entry) + sizeof(u32),\
sizeof(u64)); \
+ __entry_size -= sizeof(u32); \
\
do { \
char raw_data[__entry_size]; \