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[Qemu-devel] [PULL 1/3] trace: add syslog tracing backend
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PULL 1/3] trace: add syslog tracing backend |
Date: |
Mon, 5 Sep 2016 15:42:47 -0400 |
From: Paul Durrant <address@hidden>
This patch adds a tracing backend which sends output using syslog().
The syslog backend is limited to POSIX compliant systems.
openlog() is called with facility set to LOG_DAEMON, with the LOG_PID
option. Trace events are logged at level LOG_INFO.
Signed-off-by: Paul Durrant <address@hidden>
Message-id: address@hidden
Cc: Stefan Hajnoczi <address@hidden>
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
configure | 19 ++++++++++++++++
docs/tracing.txt | 12 ++++++++++
scripts/tracetool/backend/syslog.py | 45 +++++++++++++++++++++++++++++++++++++
trace/control.c | 7 ++++++
4 files changed, 83 insertions(+)
create mode 100644 scripts/tracetool/backend/syslog.py
diff --git a/configure b/configure
index 4b808f9..5a9bda1 100755
--- a/configure
+++ b/configure
@@ -4192,6 +4192,18 @@ if compile_prog "" "" ; then
fi
##########################################
+# check if we have posix_syslog
+
+posix_syslog=no
+cat > $TMPC << EOF
+#include <syslog.h>
+int main(void) { openlog("qemu", LOG_PID, LOG_DAEMON); syslog(LOG_INFO,
"configure"); return 0; }
+EOF
+if compile_prog "" "" ; then
+ posix_syslog=yes
+fi
+
+##########################################
# check if trace backend exists
$python "$source_path/scripts/tracetool.py" "--backends=$trace_backends"
--check-backends > /dev/null 2> /dev/null
@@ -5468,6 +5480,13 @@ if have_backend "ftrace"; then
feature_not_found "ftrace(trace backend)" "ftrace requires Linux"
fi
fi
+if have_backend "syslog"; then
+ if test "$posix_syslog" = "yes" ; then
+ echo "CONFIG_TRACE_SYSLOG=y" >> $config_host_mak
+ else
+ feature_not_found "syslog(trace backend)" "syslog not available"
+ fi
+fi
echo "CONFIG_TRACE_FILE=$trace_file" >> $config_host_mak
if test "$rdma" = "yes" ; then
diff --git a/docs/tracing.txt b/docs/tracing.txt
index 29f2f9a..e62444c 100644
--- a/docs/tracing.txt
+++ b/docs/tracing.txt
@@ -192,6 +192,18 @@ After running qemu by root user, you can get the trace:
Restriction: "ftrace" backend is restricted to Linux only.
+=== Syslog ===
+
+The "syslog" backend sends trace events using the POSIX syslog API. The log
+is opened specifying the LOG_DAEMON facility and LOG_PID option (so events
+are tagged with the pid of the particular QEMU process that generated
+them). All events are logged at LOG_INFO level.
+
+NOTE: syslog may squash duplicate consecutive trace events and apply rate
+ limiting.
+
+Restriction: "syslog" backend is restricted to POSIX compliant OS.
+
==== Monitor commands ====
* trace-file on|off|flush|set <path>
diff --git a/scripts/tracetool/backend/syslog.py
b/scripts/tracetool/backend/syslog.py
new file mode 100644
index 0000000..89019bc
--- /dev/null
+++ b/scripts/tracetool/backend/syslog.py
@@ -0,0 +1,45 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+Syslog built-in backend.
+"""
+
+__author__ = "Paul Durrant <address@hidden>"
+__copyright__ = "Copyright 2016, Citrix Systems Inc."
+__license__ = "GPL version 2 or (at your option) any later version"
+
+__maintainer__ = "Stefan Hajnoczi"
+__email__ = "address@hidden"
+
+
+from tracetool import out
+
+
+PUBLIC = True
+
+
+def generate_h_begin(events):
+ out('#include <syslog.h>',
+ '#include "trace/control.h"',
+ '')
+
+
+def generate_h(event):
+ argnames = ", ".join(event.args.names())
+ if len(event.args) > 0:
+ argnames = ", " + argnames
+
+ if "vcpu" in event.properties:
+ # already checked on the generic format code
+ cond = "true"
+ else:
+ cond = "trace_event_get_state(%s)" % ("TRACE_" + event.name.upper())
+
+ out(' if (%(cond)s) {',
+ ' syslog(LOG_INFO, "%(name)s " %(fmt)s %(argnames)s);',
+ ' }',
+ cond=cond,
+ name=event.name,
+ fmt=event.fmt.rstrip("\n"),
+ argnames=argnames)
diff --git a/trace/control.c b/trace/control.c
index d173c09..b179cde 100644
--- a/trace/control.c
+++ b/trace/control.c
@@ -19,6 +19,9 @@
#ifdef CONFIG_TRACE_LOG
#include "qemu/log.h"
#endif
+#ifdef CONFIG_TRACE_SYSLOG
+#include <syslog.h>
+#endif
#include "qapi/error.h"
#include "qemu/error-report.h"
#include "qemu/config-file.h"
@@ -250,6 +253,10 @@ bool trace_init_backends(void)
}
#endif
+#ifdef CONFIG_TRACE_SYSLOG
+ openlog(NULL, LOG_PID, LOG_DAEMON);
+#endif
+
return true;
}
--
2.7.4