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[Qemu-devel] [PULL 9/9] monitor: Reduce handle_qmp_command() tracing ove
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PULL 9/9] monitor: Reduce handle_qmp_command() tracing overhead |
Date: |
Tue, 1 Aug 2017 14:16:18 +0100 |
From: "Denis V. Lunev" <address@hidden>
We are malloc'ing a QString and spending CPU cycles on converting a
QObject to string, just for the sake of sticking the string in the trace
message. Wasted when we aren't tracing. Avoid that.
[Commit message and description suggested by Markus Armbruster to
provide more detail about the rationale for this patch.
Use trace_event_get_state_backends() instead of trace_event_get_state()
to honor DTrace/UST backend dstates.
--Stefan]
Signed-off-by: Denis V. Lunev <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
Message-id: address@hidden
CC: Stefan Hajnoczi <address@hidden>
CC: LluĂs Vilanova <address@hidden>
CC: Dr. David Alan Gilbert <address@hidden>
CC: Markus Armbruster <address@hidden>
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
monitor.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/monitor.c b/monitor.c
index 6d040e620f..e0f880107f 100644
--- a/monitor.c
+++ b/monitor.c
@@ -3823,7 +3823,6 @@ static void handle_qmp_command(JSONMessageParser *parser,
GQueue *tokens)
QDict *qdict = NULL;
Monitor *mon = cur_mon;
Error *err = NULL;
- QString *req_json;
req = json_parser_parse_err(tokens, NULL, &err);
if (!req && !err) {
@@ -3841,9 +3840,11 @@ static void handle_qmp_command(JSONMessageParser
*parser, GQueue *tokens)
qdict_del(qdict, "id");
} /* else will fail qmp_dispatch() */
- req_json = qobject_to_json(req);
- trace_handle_qmp_command(mon, qstring_get_str(req_json));
- QDECREF(req_json);
+ if (trace_event_get_state_backends(TRACE_HANDLE_QMP_COMMAND)) {
+ QString *req_json = qobject_to_json(req);
+ trace_handle_qmp_command(mon, qstring_get_str(req_json));
+ QDECREF(req_json);
+ }
rsp = qmp_dispatch(cur_mon->qmp.commands, req);
--
2.13.3
- [Qemu-devel] [PULL 0/9] Tracing patches, Stefan Hajnoczi, 2017/08/01
- [Qemu-devel] [PULL 2/9] trace: ensure unique function / variable names per .stp file, Stefan Hajnoczi, 2017/08/01
- [Qemu-devel] [PULL 1/9] trace: ensure .stp files are rebuilt if trace tool source changes, Stefan Hajnoczi, 2017/08/01
- [Qemu-devel] [PULL 3/9] trace: add TRACE_<event>_BACKEND_DSTATE(), Stefan Hajnoczi, 2017/08/01
- [Qemu-devel] [PULL 4/9] trace: add trace_event_get_state_backends(), Stefan Hajnoczi, 2017/08/01
- [Qemu-devel] [PULL 5/9] coding_style: add point about 0x in trace-events, Stefan Hajnoczi, 2017/08/01
- [Qemu-devel] [PULL 6/9] trace-events: fix code style: %# -> 0x%, Stefan Hajnoczi, 2017/08/01
- [Qemu-devel] [PULL 7/9] checkpatch: check trace-events code style, Stefan Hajnoczi, 2017/08/01
- [Qemu-devel] [PULL 9/9] monitor: Reduce handle_qmp_command() tracing overhead,
Stefan Hajnoczi <=
- [Qemu-devel] [PULL 8/9] trace-events: fix code style: print 0x before hex numbers, Stefan Hajnoczi, 2017/08/01
- Re: [Qemu-devel] [PULL 0/9] Tracing patches, no-reply, 2017/08/01
- Re: [Qemu-devel] [PULL 0/9] Tracing patches, Peter Maydell, 2017/08/01