covoar SIGKILL Investigation

[Vijay Kumar Banerjee]

I will send the attachment offlist as it's too big for the list.
On Wed, 22 Aug 2018 at 21:07, Vijay Kumar Banerjee <vijaykumar9597 at gmail.com>
wrote:

> The coverage for whole testsuite completed successfully,
> I have attached the zip file here and also included the js and css files
> in it.
>
> coverage didn't complete for the following symbol-set libraries and was
> returning,
> covoar error 10
>
> * libsapi.a
> * libposix.a
> * librfs.a
> * libcsupport.a
> * libdevnull.a
> * libblock.a
>
>
> On Wed, 22 Aug 2018 at 10:22, Chris Johns <chrisj at rtems.org> wrote:
>
>> On 22/08/2018 14:41, Joel Sherrill wrote:
>> > On Tue, Aug 21, 2018, 10:26 PM Chris Johns <chrisj at rtems.org
>> > <mailto:chrisj at rtems.org>> wrote:
>> >
>> >     On 22/08/2018 09:29, Joel Sherrill wrote:
>> >     > On Tue, Aug 21, 2018, 4:05 PM Vijay Kumar Banerjee
>> >     <vijaykumar9597 at gmail.com <mailto:vijaykumar9597 at gmail.com>
>> >     > <mailto:vijaykumar9597 at gmail.com <mailto:vijaykumar9597 at gmail.com>>>
>> wrote:
>> >     >     On Wed, 22 Aug 2018 at 01:55, Joel Sherrill <joel at rtems.org
>> >     <mailto:joel at rtems.org>
>> >     >     <mailto:joel at rtems.org <mailto:joel at rtems.org>>> wrote:
>> >     >
>> >     >         How long is covoar taking for the entire set?
>> >     >
>> >     >     It works great. this is what `time` says
>> >     >     --------
>> >     >     real17m49.887s
>> >     >     user14m25.620s
>> >     >     sys0m37.847s
>> >     >     --------
>> >     >
>> >     > What speed and type of processor do you have?
>> >     >
>> >
>> >     The program is single threaded so the preprocessing of each
>> executable is
>> >     sequential. Memory usage is reasonable so there is no swapping.
>> >
>> >     Running covoar from the command line on a box with:
>> >
>> >      hw.machine: amd64
>> >      hw.model: Intel(R) Core(TM) i7-6900K CPU @ 3.20GHz
>> >      hw.ncpu: 16
>> >      hw.machine_arch: amd64
>> >
>> >     plus 32G of memory has a time of:
>> >
>> >           366.32 real       324.97 user        41.33 sys
>> >
>> >     The approximate time break down is:
>> >
>> >      ELF/DWARF loading  : 110s (1m50s)
>> >      Objdump            : 176s (2m56s)
>> >      Processing         :  80s (1m20s)
>> >
>> >
>> > I don't mind this execution time for the near future. It is far from
>> obscene
>> > after building and running 600 tests.
>>
>> Yeah, there are other things we need to do first.
>>
>> >     The DWARF loading is not optimised and I load all source line to
>> address maps
>> >     and all functions rather that selectively scanning for specific
>> names at the
>> >     DWARF level. It is not clear to me scanning would be better or
>> faster.
>> >
>> > I doubt it is worth the effort. There should be few symbols in an exe
>> we don't
>> > care about. Especially once we start to worry about libc and libm.
>>
>> Yeah, this is what I thought at the start.
>>
>> >     My hope
>> >     is moving to Capstone would help lower or remove the objdump
>> overhead. Then
>> >     there is threading for the loading.
>> >
>> >     > I don't recall it taking near this long in the past. I used to
>> run it as
>> >     part of
>> >     > development.
>> >
>> >     The objdump processing is simpler than before so I suspect the time
>> would have
>> >     been at least 4 minutes.
>> >
>> >     > But we may have more tests and the code has changed.
>> >
>> >     I think having more tests is the dominant factor.
>> >
>> >     > Reading dwarf
>> >     > with the file open/closes, etc just may be more expensive than
>> parsing the
>> >     text
>> >     > files.
>> >
>> >     The reading DWARF is a cost and at the moment it is not optimised
>> but it is only
>> >     a cost because we still parse the objdump data. I think opening and
>> closing
>> >     files is not a factor.
>> >
>> >     The parsing the objdump is the largest component of time. Maybe
>> using Capstone
>> >     with the ELF files will help.
>> >
>> >     > But it is more accurate and lays the groundwork.for more types of
>> analysis.
>> >
>> >     Yes and think this is important.
>> >
>> > +1
>> >
>> >     > Eventually we will have to profile this code. Whatever is costly
>> is done for
>> >     > each exe so there is a multiplier.
>> >     >
>> >     > I suspect this code would parallelize reading info from the exes
>> fairly well.
>> >
>> >     Agreed.
>> >
>> > Might be a good case for C++11 threads if one of the thread container
>> classes is
>> > a nice pool.
>>
>> Good idea. I think we need to look at some of the global object pointers
>> before
>> we head down this path.
>>
>> > And we might have some locking to account for in core data structures.
>> Are STL
>> > container instances thread safe?
>>
>> We need to manage all locking.
>>
>> > But an addition after feature stable relative to old output plus
>> Capstone.
>>
>> Agreed.
>>
>> >     > Merging the info and generating the reports not well due to data
>> contention.
>> >
>> >     Yes.
>> >
>> >     > But optimizing too early and the wrong way is not smart.
>> >
>> >     Yes. We need Capstone to be added before this can happen.
>> >
>> > +1
>> >
>> > I would also like to see gcov support but that will not be a factor in
>> the
>> > performance we have. It will add reading a lot more files (gcno) and
>> writing a
>> > lot of gcda at the end. Again more important to be right than fast at
>> first. And
>> > completely an addition.
>>
>> Agreed.
>>
>> Chris
>>
>
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