From 304703aba31a87903b8c0db8f5e6890cac2d596d Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Mon, 10 Aug 2009 16:11:32 +0200 Subject: [PATCH] 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 Acked-by: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Cc: Mike Galbraith Cc: Paul Mackerras LKML-Reference: <20090810141129.GA5124@nowhere> Signed-off-by: Ingo Molnar --- include/trace/ftrace.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h index 7167b9b97da2..a05524fa245d 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_(&__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]; \ -- 2.30.2