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[Qemu-devel] [PATCH] simpletrace: Inline runtime state check
From: |
Jan Kiszka |
Subject: |
[Qemu-devel] [PATCH] simpletrace: Inline runtime state check |
Date: |
Tue, 19 Oct 2010 16:14:09 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
Instead of preparing all traced args, jumping into the common trace
function, even collecting a timestamp, do the check if a particular
tracepoint is enabled inline. Also, mark the enabled case unlikely to
motivate the compiler to push the trace code out of the fastpath.
Signed-off-by: Jan Kiszka <address@hidden>
---
simpletrace.c | 4 ----
tracetool | 7 +++++--
2 files changed, 5 insertions(+), 6 deletions(-)
diff --git a/simpletrace.c b/simpletrace.c
index deb1e07..224e4ab 100644
--- a/simpletrace.c
+++ b/simpletrace.c
@@ -148,10 +148,6 @@ static void trace(TraceEventID event, uint64_t x1,
uint64_t x2, uint64_t x3,
*/
clock_gettime(CLOCK_MONOTONIC, &ts);
- if (!trace_list[event].state) {
- return;
- }
-
rec->event = event;
rec->timestamp_ns = ts.tv_sec * 1000000000LL + ts.tv_nsec;
rec->x1 = x1;
diff --git a/tracetool b/tracetool
index 7010858..9532409 100755
--- a/tracetool
+++ b/tracetool
@@ -146,6 +146,8 @@ linetoh_begin_simple()
{
cat <<EOF
#include "simpletrace.h"
+
+extern TraceEvent trace_list[];
EOF
simple_event_num=0
@@ -179,7 +181,9 @@ linetoh_simple()
cat <<EOF
static inline void trace_$name($args)
{
- trace$argc($trace_args);
+ if (unlikely(trace_list[$simple_event_num].state)) {
+ trace$argc($trace_args);
+ }
}
EOF
@@ -190,7 +194,6 @@ linetoh_end_simple()
{
cat <<EOF
#define NR_TRACE_EVENTS $simple_event_num
-extern TraceEvent trace_list[NR_TRACE_EVENTS];
EOF
}
--
1.7.1
- [Qemu-devel] [PATCH] simpletrace: Inline runtime state check,
Jan Kiszka <=