Commit 0a852417 authored by Paul Durrant's avatar Paul Durrant Committed by Stefan Hajnoczi
Browse files

trace: add syslog tracing backend 



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: default avatarPaul Durrant <paul.durrant@citrix.com>
Message-id: 1470318254-29989-1-git-send-email-paul.durrant@citrix.com
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent e87d397e

configure

+19 −0
Original line number Diff line number Diff line
@@ -4191,6 +4191,18 @@ if compile_prog "" "" ; then 
    posix_madvise=yes

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
@@ -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

docs/tracing.txt

+12 −0
Original line number Diff line number Diff line
@@ -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>

scripts/tracetool/backend/syslog.py

0 → 100644
+45 −0
Original line number Diff line number Diff line 
#!/usr/bin/env python

# -*- coding: utf-8 -*-



"""

Syslog built-in backend.

"""



__author__     = "Paul Durrant <paul.durrant@citrix.com>"

__copyright__  = "Copyright 2016, Citrix Systems Inc."

__license__    = "GPL version 2 or (at your option) any later version"



__maintainer__ = "Stefan Hajnoczi"

__email__      = "stefanha@redhat.com"





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)

trace/control.c

+7 −0
Original line number Diff line number Diff line
@@ -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;

}