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From:   Anup Sharma <anupnewsmail@gmail.com>
Date:   Mon, 17 Jul 2023 21:42:32 +0530
To:     Ian Rogers <irogers@google.com>
Cc:     Anup Sharma <anupnewsmail@gmail.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Adrian Hunter <adrian.hunter@intel.com>,
        linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 6/6] scripts: python: implement get or create frame
 and stack function
Message-ID: <ZLVocFUFMgquEJDY@yoga>
References: <cover.1689024635.git.anupnewsmail@gmail.com>
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On Wed, Jul 12, 2023 at 10:44:21AM -0700, Ian Rogers wrote:
> On Mon, Jul 10, 2023 at 4:15 PM Anup Sharma <anupnewsmail@gmail.com> wrote:
> >
> > Complete addSample function, it takes the thread name, stack array,
> > and time as input parameters and  if the thread name differs from
> > the current name, it updates the name. The function utilizes the
> > get_or_create_stack and get_or_create_frame methods to construct
> > the stack structure. Finally, it adds the stack, time, and
> > responsiveness values to the 'data' list within 'samples'.
> >
> > The get_or_create_stack function is responsible for retrieving
> > or creating a stack based on the provided frame and prefix.
> > It first generates a key using the frame and prefix values.
> > If the stack corresponding to the key is found in the stackMap,
> > it is returned. Otherwise, a new stack is created by appending
> > the prefix and frame to the stackTable's 'data' array. The key
> > and the index of the newly created stack are added to the
> > stackMap for future reference.
> >
> > The get_or_create_frame function is responsible for retrieving or
> > creating a frame based on the provided frameString. If the frame
> > corresponding to the frameString is found in the frameMap, it is
> > returned. Otherwise, a new frame is created by appending relevant
> > information to the frameTable's 'data' array and adding the
> > frameString to the stringTable.
> >
> > Signed-off-by: Anup Sharma <anupnewsmail@gmail.com>
> > ---
> >  .../scripts/python/firefox-gecko-converter.py | 57 ++++++++++++++++++-
> >  1 file changed, 56 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/perf/scripts/python/firefox-gecko-converter.py b/tools/perf/scripts/python/firefox-gecko-converter.py
> > index 6c934de1f608..97fbe562ee2b 100644
> > --- a/tools/perf/scripts/python/firefox-gecko-converter.py
> > +++ b/tools/perf/scripts/python/firefox-gecko-converter.py
> > @@ -21,6 +21,8 @@ sys.path.append(os.environ['PERF_EXEC_PATH'] + \
> >  from perf_trace_context import *
> >  from Core import *
> >
> > +USER_CATEGORY_INDEX = 0
> > +KERNEL_CATEGORY_INDEX = 1
> >  thread_map = {}
> >  start_time = None
> >
> > @@ -34,7 +36,12 @@ CATEGORIES = [
> >  PRODUCT = os.popen('uname -op').read().strip()
> >
> >  def trace_end():
> > -    thread_array = thread_map.values()))
> > +    thread_array = list(map(lambda thread: thread['finish'](), thread_map.values()))
> 
> With a class this will be a more intuitive:
> 
> thread.finish()

I have made the changes. Thanks for the suggestion.

> > +
> > +# Parse the callchain of the current sample into a stack array.
> > +    for thread in thread_array:
> > +        key = thread['samples']['schema']['time']
> 
> I'm not sure what 'schema' is here. Worth a comment.

Thanks, I am planning to add hyper-link as a the comment. Like this:
# https://github.com/firefox-devtools/profiler/blob/53970305b51b9b472e26d7457fee1d66cd4e2737/src/types/gecko-profile.js#L216
However it is going to exceed 100 characters limit. If I wrap it
around, it will look ugly. Any suggestions?

> 
> > +        thread['samples']['data'].sort(key=lambda data : float(data[key]))
> 
> Perhaps there is a more intention revealing name than "data".

Noted. I will change it.

> >
> >      result = {
> >          'meta': {
> > @@ -106,7 +113,55 @@ def process_event(param_dict):
> >                 }
> >                 stringTable = []
> >
> > +               stackMap = dict()
> > +               def get_or_create_stack(frame, prefix):
> 
> Can you comment what frame and prefix are with examples, otherwise
> understanding this function is hard.

I am using more descriptive names now. I have also added a comment like
this to the function:
"""Gets a matching stack, or saves the new stack. Returns a Stack ID."""
Will be reflected in v4.

> > +                       key = f"{frame}" if prefix is None else f"{frame},{prefix}"
> > +                       stack = stackMap.get(key)
> > +                       if stack is None:
> > +                               stack = len(stackTable['data'])
> > +                               stackTable['data'].append([prefix, frame])
> > +                               stackMap[key] = stack
> > +                       return stack
> > +
> > +               frameMap = dict()
> > +               def get_or_create_frame(frameString):
> 
> s/frameMap/frame_map/
> s/frameString/frame_string/
> 
> These variable names aren't going a long way to helping understand the
> code. They mention frame and then the type, which should really be
> type information like ": Dict[...]". Can you improve the names as
> otherwise we effectively have 3 local variables all called "frame".

I have made the changes. Thanks for the suggestion.

> > +                       frame = frameMap.get(frameString)
> > +                       if frame is None:
> > +                               frame = len(frameTable['data'])
> > +                               location = len(stringTable)
> > +                               stringTable.append(frameString)
> > +                               category = KERNEL_CATEGORY_INDEX if frameString.find('kallsyms') != -1 \
> > +                                               or frameString.find('/vmlinux') != -1 \
> > +                                               or frameString.endswith('.ko)') \
> > +                                               else USER_CATEGORY_INDEX
> 
> Perhaps make this a helper function, symbol_name_to_category_index.

I am trying to find if I can use cpu_mode instead of this as suggested by
Namhyung. If not, I will add a helper function in the later version.

> > +                               implementation = None
> > +                               optimizations = None
> > +                               line = None
> > +                               relevantForJS = False
> 
> Some comments on these variables would be useful, perhaps just use
> named arguments below.

Okay, this variable comes from Gecko format, now adding link might
make it understandable.

> > +                               subcategory = None
> > +                               innerWindowID = 0
> > +                               column = None
> > +
> > +                               frameTable['data'].append([
> > +                                       location,
> > +                                       relevantForJS,
> > +                                       innerWindowID,
> > +                                       implementation,
> > +                                       optimizations,
> > +                                       line,
> > +                                       column,
> > +                                       category,
> > +                                       subcategory,
> > +                               ])
> > +                               frameMap[frameString] = frame
> > +                       return frame
> > +
> >                 def addSample(threadName, stackArray, time):
> > +                       nonlocal name
> > +                       if name != threadName:
> > +                               name = threadName
> 
> A comment/example would be useful here.

Noted.

> 
> > +                       stack = reduce(lambda prefix, stackFrame: get_or_create_stack
> > +                                       (get_or_create_frame(stackFrame), prefix), stackArray, None)
> 
> Thanks,
> Ian
> 
> >                         responsiveness = 0
> >                         samples['data'].append([stack, time, responsiveness])
> >
> > --
> > 2.34.1
> >