[Qemu-devel] [PATCH] trace: teach lttng backend to use format strings

[Qemu-devel] [PATCH] trace: teach lttng backend to use format strings

[alex.bennee]

From: Alex Bennée <alex.bennee@linaro.org>

This makes the UST backend pay attention to the format string arguments
that are defined when defining payload data. With this you can now
ensure integers are reported in hex mode if you want.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
---
 scripts/tracetool/__init__.py    | 13 +++++++++++--
 scripts/tracetool/backend/ust.py | 16 ++++++++++++----
 2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/scripts/tracetool/__init__.py b/scripts/tracetool/__init__.py
index 175df08..abcdc49 100644
--- a/scripts/tracetool/__init__.py
+++ b/scripts/tracetool/__init__.py
@@ -118,13 +118,16 @@ class Event(object):
         Properties of the event.
     args : Arguments
         The event arguments.
+    arg_fmts : str
+        The format strings for each arugment.
     """
 
     _CRE = re.compile("((?P<props>.*)\s+)?(?P<name>[^(\s]+)\((?P<args>[^)]*)\)\s*(?P<fmt>\".*)?")
+    _FMT = re.compile("(%\w+|%.*PRI\S+)")
 
     _VALID_PROPS = set(["disable"])
 
-    def __init__(self, name, props, fmt, args):
+    def __init__(self, name, props, fmt, args, arg_fmts):
         """
         Parameters
         ----------
@@ -136,11 +139,15 @@ class Event(object):
             Event printing format.
         args : Arguments
             Event arguments.
+        arg_fmts : list of str
+            Format strings for each argument
+
         """
         self.name = name
         self.properties = props
         self.fmt = fmt
         self.args = args
+        self.arg_fmts = arg_fmts
 
         unknown_props = set(self.properties) - self._VALID_PROPS
         if len(unknown_props) > 0:
@@ -163,8 +170,10 @@ class Event(object):
         props = groups["props"].split()
         fmt = groups["fmt"]
         args = Arguments.build(groups["args"])
+        print "%s: %s and %s" % (name, args, fmt)
+        arg_fmts = Event._FMT.findall(fmt)
 
-        return Event(name, props, fmt, args)
+        return Event(name, props, fmt, args, arg_fmts)
 
     def __repr__(self):
         """Evaluable string representation for this object."""
diff --git a/scripts/tracetool/backend/ust.py b/scripts/tracetool/backend/ust.py
index 41c1c75..cb09958 100644
--- a/scripts/tracetool/backend/ust.py
+++ b/scripts/tracetool/backend/ust.py
@@ -56,13 +56,21 @@ def ust_events_h(events):
                 args = ", ".join(", ".join(i) for i in e.args),
                 )
 
-            for t,n in e.args:
-                if ('int' in t) or ('long' in t) or ('unsigned' in t) or ('size_t' in t):
+            types = e.args.types()
+            names = e.args.names()
+            fmts = e.arg_fmts
+            print "/* %s/%s/%s */" % (types, names, fmts)
+            for t,n,f in zip(types, names, fmts):
+                if ('char *' in t) or ('char*' in t):
+                    out('       ctf_string(' + n + ', ' + n + ')')
+                elif ("%p" in f) or ("x" in f) or ("PRIx" in f):
+                    out('       ctf_integer_hex('+ t + ', ' + n + ', ' + n + ')')
+                elif ("ptr" in t) or ("*" in t):
+                    out('       ctf_integer_hex('+ t + ', ' + n + ', ' + n + ')')
+                elif ('int' in t) or ('long' in t) or ('unsigned' in t) or ('size_t' in t):
                     out('       ctf_integer(' + t + ', ' + n + ', ' + n + ')')
                 elif ('double' in t) or ('float' in t):
                     out('       ctf_float(' + t + ', ' + n + ', ' + n + ')')
-                elif ('char *' in t) or ('char*' in t):
-                    out('       ctf_string(' + n + ', ' + n + ')')
                 elif ('void *' in t) or ('void*' in t):
                     out('       ctf_integer_hex(unsigned long, ' + n + ', ' + n + ')')
 
-- 
1.9.1

[Qemu-devel] [PATCH] trace: teach lttng backend to use format strings

[alex.bennee]

From: Alex Bennée <alex.bennee@linaro.org>

This makes the UST backend pay attention to the format string arguments
that are defined when defining payload data. With this you can now
ensure integers are reported in hex mode if you want.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

---

v2
  - remove silly debug statements
---
 scripts/tracetool/__init__.py    | 12 ++++++++++--
 scripts/tracetool/backend/ust.py | 17 ++++++++++++-----
 2 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/scripts/tracetool/__init__.py b/scripts/tracetool/__init__.py
index 175df08..71e2ab5 100644
--- a/scripts/tracetool/__init__.py
+++ b/scripts/tracetool/__init__.py
@@ -118,13 +118,16 @@ class Event(object):
         Properties of the event.
     args : Arguments
         The event arguments.
+    arg_fmts : str
+        The format strings for each arugment.
     """
 
     _CRE = re.compile("((?P<props>.*)\s+)?(?P<name>[^(\s]+)\((?P<args>[^)]*)\)\s*(?P<fmt>\".*)?")
+    _FMT = re.compile("(%\w+|%.*PRI\S+)")
 
     _VALID_PROPS = set(["disable"])
 
-    def __init__(self, name, props, fmt, args):
+    def __init__(self, name, props, fmt, args, arg_fmts):
         """
         Parameters
         ----------
@@ -136,11 +139,15 @@ class Event(object):
             Event printing format.
         args : Arguments
             Event arguments.
+        arg_fmts : list of str
+            Format strings for each argument
+
         """
         self.name = name
         self.properties = props
         self.fmt = fmt
         self.args = args
+        self.arg_fmts = arg_fmts
 
         unknown_props = set(self.properties) - self._VALID_PROPS
         if len(unknown_props) > 0:
@@ -163,8 +170,9 @@ class Event(object):
         props = groups["props"].split()
         fmt = groups["fmt"]
         args = Arguments.build(groups["args"])
+        arg_fmts = Event._FMT.findall(fmt)
 
-        return Event(name, props, fmt, args)
+        return Event(name, props, fmt, args, arg_fmts)
 
     def __repr__(self):
         """Evaluable string representation for this object."""
diff --git a/scripts/tracetool/backend/ust.py b/scripts/tracetool/backend/ust.py
index 41c1c75..6223f20 100644
--- a/scripts/tracetool/backend/ust.py
+++ b/scripts/tracetool/backend/ust.py
@@ -56,13 +56,20 @@ def ust_events_h(events):
                 args = ", ".join(", ".join(i) for i in e.args),
                 )
 
-            for t,n in e.args:
-                if ('int' in t) or ('long' in t) or ('unsigned' in t) or ('size_t' in t):
+            types = e.args.types()
+            names = e.args.names()
+            fmts = e.arg_fmts
+            for t,n,f in zip(types, names, fmts):
+                if ('char *' in t) or ('char*' in t):
+                    out('       ctf_string(' + n + ', ' + n + ')')
+                elif ("%p" in f) or ("x" in f) or ("PRIx" in f):
+                    out('       ctf_integer_hex('+ t + ', ' + n + ', ' + n + ')')
+                elif ("ptr" in t) or ("*" in t):
+                    out('       ctf_integer_hex('+ t + ', ' + n + ', ' + n + ')')
+                elif ('int' in t) or ('long' in t) or ('unsigned' in t) or ('size_t' in t):
                     out('       ctf_integer(' + t + ', ' + n + ', ' + n + ')')
                 elif ('double' in t) or ('float' in t):
                     out('       ctf_float(' + t + ', ' + n + ', ' + n + ')')
-                elif ('char *' in t) or ('char*' in t):
-                    out('       ctf_string(' + n + ', ' + n + ')')
                 elif ('void *' in t) or ('void*' in t):
                     out('       ctf_integer_hex(unsigned long, ' + n + ', ' + n + ')')
 
@@ -79,4 +86,4 @@ def ust_events_h(events):
                 ')',
                 '',
                 name = e.name,
-                )
\ No newline at end of file
+                )
-- 
1.9.1

Re: [Qemu-devel] [PATCH] trace: teach lttng backend to use format strings

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 647 bytes --]

On 03/24/2014 11:35 AM, alex.bennee@linaro.org wrote:
> From: Alex Bennée <alex.bennee@linaro.org>
> 
> This makes the UST backend pay attention to the format string arguments
> that are defined when defining payload data. With this you can now
> ensure integers are reported in hex mode if you want.
> 
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> 
> ---

>      args : Arguments
>          The event arguments.
> +    arg_fmts : str
> +        The format strings for each arugment.

s/arugment/argument/

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH] trace: teach lttng backend to use format strings

[Stefan Hajnoczi]

On Mon, Mar 24, 2014 at 05:35:26PM +0000, alex.bennee@linaro.org wrote:
> From: Alex Bennée <alex.bennee@linaro.org>
> 
> This makes the UST backend pay attention to the format string arguments
> that are defined when defining payload data. With this you can now
> ensure integers are reported in hex mode if you want.
> 
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> 
> ---
> 
> v2
>   - remove silly debug statements
> ---
>  scripts/tracetool/__init__.py    | 12 ++++++++++--
>  scripts/tracetool/backend/ust.py | 17 ++++++++++++-----
>  2 files changed, 22 insertions(+), 7 deletions(-)

This conflicts with Lluis' tracing cleanup patch series that is merged
for QEMU 2.1.

Please rebase on:

  git://github.com/stefanha/qemu.git tracing-next

Re: [Qemu-devel] [PATCH] trace: teach lttng backend to use format strings

[Stefan Hajnoczi]

On Mon, Mar 24, 2014 at 05:04:54PM +0000, alex.bennee@linaro.org wrote:
> From: Alex Bennée <alex.bennee@linaro.org>
> 
> This makes the UST backend pay attention to the format string arguments
> that are defined when defining payload data. With this you can now
> ensure integers are reported in hex mode if you want.
> 
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> ---
>  scripts/tracetool/__init__.py    | 13 +++++++++++--
>  scripts/tracetool/backend/ust.py | 16 ++++++++++++----
>  2 files changed, 23 insertions(+), 6 deletions(-)

How are strings handled, can LTTng copy them from the QEMU process'
memory space?

Stefan

Re: [Qemu-devel] [PATCH] trace: teach lttng backend to use format strings

[Alex Bennée]

Stefan Hajnoczi <stefanha@redhat.com> writes:

> On Mon, Mar 24, 2014 at 05:04:54PM +0000, alex.bennee@linaro.org wrote:
>> From: Alex Bennée <alex.bennee@linaro.org>
>> 
>> This makes the UST backend pay attention to the format string arguments
>> that are defined when defining payload data. With this you can now
>> ensure integers are reported in hex mode if you want.
>> 
>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>> ---
>>  scripts/tracetool/__init__.py    | 13 +++++++++++--
>>  scripts/tracetool/backend/ust.py | 16 ++++++++++++----
>>  2 files changed, 23 insertions(+), 6 deletions(-)
>
> How are strings handled, can LTTng copy them from the QEMU process'
> memory space?

lttng provides ctf_string for passing strings to the payload. But I
wouldn't expect to use them for the result of format string calculations
as that would defeat the point of the low impact tracing.

There are a number of trace-events that pass strings for various things.
I've not actually experimented with the output of any of them though.


>
> Stefan

-- 
Alex Bennée

Re: [Qemu-devel] [PATCH] trace: teach lttng backend to use format strings

[Stefan Hajnoczi]

On Tue, Mar 25, 2014 at 02:49:42PM +0000, Alex Bennée wrote:
> 
> Stefan Hajnoczi <stefanha@redhat.com> writes:
> 
> > On Mon, Mar 24, 2014 at 05:04:54PM +0000, alex.bennee@linaro.org wrote:
> >> From: Alex Bennée <alex.bennee@linaro.org>
> >> 
> >> This makes the UST backend pay attention to the format string arguments
> >> that are defined when defining payload data. With this you can now
> >> ensure integers are reported in hex mode if you want.
> >> 
> >> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> >> ---
> >>  scripts/tracetool/__init__.py    | 13 +++++++++++--
> >>  scripts/tracetool/backend/ust.py | 16 ++++++++++++----
> >>  2 files changed, 23 insertions(+), 6 deletions(-)
> >
> > How are strings handled, can LTTng copy them from the QEMU process'
> > memory space?
> 
> lttng provides ctf_string for passing strings to the payload. But I
> wouldn't expect to use them for the result of format string calculations
> as that would defeat the point of the low impact tracing.
> 
> There are a number of trace-events that pass strings for various things.
> I've not actually experimented with the output of any of them though.

Sounds like it should work but can you test it?  Try enabling the
bdrv_open_common() trace event when booting a guest.  You should see the
filename of the disk image file.

Stefan

Re: [Qemu-devel] [PATCH] trace: teach lttng backend to use format strings

[Mohamad Gebai]

I can confirm that it works for me, I can see the disk image file name 
in the payload of brdv_open_common events.

Mohamad

On 03/26/2014 04:27 AM, Stefan Hajnoczi wrote:
> On Tue, Mar 25, 2014 at 02:49:42PM +0000, Alex Bennée wrote:
>> Stefan Hajnoczi <stefanha@redhat.com> writes:
>>
>>> On Mon, Mar 24, 2014 at 05:04:54PM +0000, alex.bennee@linaro.org wrote:
>>>> From: Alex Bennée <alex.bennee@linaro.org>
>>>>
>>>> This makes the UST backend pay attention to the format string arguments
>>>> that are defined when defining payload data. With this you can now
>>>> ensure integers are reported in hex mode if you want.
>>>>
>>>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>>>> ---
>>>>   scripts/tracetool/__init__.py    | 13 +++++++++++--
>>>>   scripts/tracetool/backend/ust.py | 16 ++++++++++++----
>>>>   2 files changed, 23 insertions(+), 6 deletions(-)
>>> How are strings handled, can LTTng copy them from the QEMU process'
>>> memory space?
>> lttng provides ctf_string for passing strings to the payload. But I
>> wouldn't expect to use them for the result of format string calculations
>> as that would defeat the point of the low impact tracing.
>>
>> There are a number of trace-events that pass strings for various things.
>> I've not actually experimented with the output of any of them though.
> Sounds like it should work but can you test it?  Try enabling the
> bdrv_open_common() trace event when booting a guest.  You should see the
> filename of the disk image file.
>
> Stefan