Re: Can you write code directly in CIL ???


"Pohihihi" <noemail@xxxxxxxxxxx> wrote in message
news:e5TKP%23qCGHA.516@xxxxxxxxxxxxxxxxxxxxxxx
> Your benchmarking on perfomance is bit off posting to posting. If it is 100
> lines of code in asm then surely it will be performing better but how many
> lines of .NET conversion of it. But if you are saying 100 lines of code in
> .Net then I wonder how many lines of instruction code your .net code is
> creating to execute it several million times in a given second or 10 of a
> second or which ever benchmark is correct.
It is currently writtten is Visual C++ 6.0 I tried compiling it with Visual C++
7.0, but this compiler produces poorer code quality by failing to inline
functions. My discussion of .NET is hypothetical. I am going to translate the
unmanaged C++ into managed C#. It is about 100 lines of unmanaged C++ now. This
will translate into about 100 lines of managed C#.

>
> Well anyways, seems like you know the ground you are playing on so for the
> answer for your original question, yes you can write the whole program in IL.
> I will be interested in knowing how you optimized it.
>
>
>
>
> "Peter Olcott" <olcott@xxxxxxx> wrote in message
> news:4S4sf.37937$QW2.7702@xxxxxxxxxxxxx
>> Not only will it run several million times every second, but, it will
>> constantly access all of its memory. Can I write a .NET component using
>> purely unmanaged code? That would seem to be a contradiction in terms.
>>
>> "Pohihihi" <noemail@xxxxxxxxxxx> wrote in message
>> news:e6$JcnqCGHA.916@xxxxxxxxxxxxxxxxxxxxxxx
>>> IMHO and according to the following link GC is way better than traditional
>>> memory mgmt. If method is running many million times a second (really??)
>>> then GC will keep it. But as Nicholas said, running of GC is a overhead and
>>> it is in control of CLR. Just because your code knows how much memory it
>>> needs it really do not mean that it will always have that in hand. Again GC
>>> is god here. If you want control of your code and how it behaves than leave
>>> managed environment and go for traditional C++/C/ASM route, or as suggested
>>> Interop.
>>>
>>> http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dndotnet/html/dotnetperftechs.asp
>>> section -->
>>> "Myth: Garbage Colloction Is Always Slower Than Doing It by Hand"
>>>
>>>
>>>
>>>
>>>
>>> "Nicholas Paldino [.NET/C# MVP]" <mvp@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in
>>> message news:%23YB$FaqCGHA.3820@xxxxxxxxxxxxxxxxxxxxxxx
>>>> Peter,
>>>>
>>>> You are missing the point completely. If you implement your code as
>>>> managed code, even in IL, you can't stop a GC no matter what. Your thread
>>>> is going to be pre-empted (in most situations, except if you have the GC
>>>> running on a separate thread) and it WILL stop and it WILL affect your
>>>> performance when it happens.
>>>>
>>>> Just because your code knows how much memory it needs doesn't mean that
>>>> you can pre-empt a GC. If it happens, it's going to happen, and there is
>>>> nothing you can do about it. Your 100-line function isn't going to be able
>>>> to stop it, and the CLR isn't going to care what your function is doing.
>>>>
>>>> You can't just pretend its not going to happen. It does, and it will,
>>>> and you can't stop it. This isn't a choice you have if you are running
>>>> managed code, whether you do it in IL or not.
>>>>
>>>> This is what it means to have ^managed^ code. The CLR is going to
>>>> provide a good number of services, but you are going to have to pay for
>>>> them, and should be aware of how they impact your code.
>>>>
>>>> This is why I recommended that you use interop with your unmanaged code.
>>>> You will have your performance requirements fufilled, and not have to worry
>>>> about doing something that will ultimately be self-defeating.
>>>>
>>>> --
>>>> - Nicholas Paldino [.NET/C# MVP]
>>>> - mvp@xxxxxxxxxxxxxxxxxxxxxxxxxxx
>>>>
>>>> "Peter Olcott" <olcott@xxxxxxx> wrote in message
>>>> news:GV3sf.37927$QW2.2410@xxxxxxxxxxxxx
>>>>>
>>>>> "Nicholas Paldino [.NET/C# MVP]" <mvp@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote
>>>>> in message news:uvvaatpCGHA.4004@xxxxxxxxxxxxxxxxxxxxxxx
>>>>>> Peter,
>>>>>>
>>>>>> You don't understand a fundamental concept to .NET and CIL. Yes,
>>>>>> there are compilers that will perform optimization of IL to a certain
>>>>>> degree.
>>>>>>
>>>>>> However, when the managed code is run, the CLR will take the CIL and
>>>>>> then compile it into native code. At this point in time, it is free to
>>>>>> optimize, or not optimize, or mangle your code in any way you want when
>>>>>> making the transition from CIL to native code.
>>>>>>
>>>>>> When you are dealing with assembly language in general, you have
>>>>>> complete control of what is going on, memory allocation, deallocation,
>>>>>> execution, etc, etc. With the CLR, this is taken out of your hands to a
>>>>>> degree.
>>>>>
>>>>> I don't care about these things they are not effecting my performance.
>>>>> What is effecting my performance are things such as the compiler failing
>>>>> to inline my functions code, and unnecessary overhead in the translation
>>>>> of a switch statement. My function will be always executed several million
>>>>> times every second. It must run concurrently with other applications.
>>>>>
>>>>>>
>>>>>> For example, have you considered, what happens when a Garbage
>>>>>> Collection (GC) occurs while your function is running? If it is in
>>>>>> complete managed code, then there is nothing that you can do about it,
>>>>>> and your function will resume running when the GC is complete. Depending
>>>>>> on what is happening on the machine at the time, combined with what your
>>>>>> program is doing, etc, etc, it is very feasible that your code will take
>>>>>> more than 1/10th of a second.
>>>>> My code knows exactly how much memory it needs at load time. It needs all
>>>>> of this memory the whole time that it executes. It would make no sense to
>>>>> have any garbage collection of my code's memory in this case. I want my
>>>>> code to be implemented as a .ET component.
>>>>>
>>>>>>
>>>>>> Just because it looks like assembly language, don't assume that CIL is
>>>>>> assembly language. There are some very different things going on under
>>>>>> the hood.
>>>>>>
>>>>>> --
>>>>>> - Nicholas Paldino [.NET/C# MVP]
>>>>>> - mvp@xxxxxxxxxxxxxxxxxxxxxxxxxxx
>>>>>>
>>>>>> "Peter Olcott" <olcott@xxxxxxx> wrote in message
>>>>>> news:xj2sf.37906$QW2.34052@xxxxxxxxxxxxx
>>>>>>>I want to be able to stick with purely managed code, if possible. I just
>>>>>>>need this 100 line function to run as fast as if it was hand tweaked
>>>>>>>assembly language. I have examined CIL, for the most part it is
>>>>>>>essentially assembly language. From what I understand any optimizations
>>>>>>>take place before the CIL is generated. When I designed this system (in
>>>>>>>1998) I had hand tweaked assembly language in mind for this crucial
>>>>>>>function all along.
>>>>>>>
>>>>>>> "Nicholas Paldino [.NET/C# MVP]" <mvp@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote
>>>>>>> in message news:%23RjK3$oCGHA.2040@xxxxxxxxxxxxxxxxxxxxxxx
>>>>>>>> Peter,
>>>>>>>>
>>>>>>>> Not at all. When the CLR gets a hold of the JIT, it is free to
>>>>>>>> perform any optimizations it deems necessary, and that might not
>>>>>>>> necessarily be in line with what you are expecting.
>>>>>>>>
>>>>>>>> My recommendation would be to use Managed C++ to create a wrapper to
>>>>>>>> your unmanaged code which uses It Just Works (IJW, seriously). You
>>>>>>>> should get a managed interface, and the best possible performance (for
>>>>>>>> this specific situation, not all situations) between managed an
>>>>>>>> unmanaged code.
>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>> - Nicholas Paldino [.NET/C# MVP]
>>>>>>>> - mvp@xxxxxxxxxxxxxxxxxxxxxxxxxxx
>>>>>>>>
>>>>>>>> "Peter Olcott" <olcott@xxxxxxx> wrote in message
>>>>>>>> news:_51sf.37898$QW2.37853@xxxxxxxxxxxxx
>>>>>>>>>I need the best possible execution speed. I have found that there is a
>>>>>>>>>large difference in the quality of the code generated by the various
>>>>>>>>>compilers. I have 16,000 hours of development time in my current
>>>>>>>>>project. There is a 100 line function that must take no longer than
>>>>>>>>>1/10 second to execute. I can just barely achieve this with MSVC++ 6.0.
>>>>>>>>>MSVC++ 7.0 has had some of its optimizations disabled. I eventually
>>>>>>>>>will need to port this to C# .NET. This is a case where hand tweaked
>>>>>>>>>assembly language would be appropriate. I figured that hand tweaked CIL
>>>>>>>>>would be the .NET equivalent of hand tweaked assembly language.
>>>>>>>>>
>>>>>>>>> "Nicholas Paldino [.NET/C# MVP]" <mvp@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
>>>>>>>>> wrote in message news:OCvd7unCGHA.2644@xxxxxxxxxxxxxxxxxxxxxxx
>>>>>>>>>> Peter,
>>>>>>>>>>
>>>>>>>>>> You can write it, but you would have to create a module with IL,
>>>>>>>>>> and then compile that into your assembly (or just write the whole
>>>>>>>>>> assembly).
>>>>>>>>>>
>>>>>>>>>> Also, what optimizations do you think you can make? Ultimately,
>>>>>>>>>> you suffer from the fact that Windows is not a real-time OS, and
>>>>>>>>>> nothing you can do will change that. On top of that, the JIT is
>>>>>>>>>> what's going to optimize your code again after you try to, so you
>>>>>>>>>> might actually end up hurting yourself more than helping yourself.
>>>>>>>>>>
>>>>>>>>>> If you post the code you are trying to optimize, we can try and
>>>>>>>>>> tell you where you might make some improvements, but dipping down to
>>>>>>>>>> the IL level is most likely not going to help you much.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> --
>>>>>>>>>> - Nicholas Paldino [.NET/C# MVP]
>>>>>>>>>> - mvp@xxxxxxxxxxxxxxxxxxxxxxxxxxx
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> "Peter Olcott" <olcott@xxxxxxx> wrote in message
>>>>>>>>>> news:7t%rf.37887$QW2.9998@xxxxxxxxxxxxx
>>>>>>>>>>> Cab you write code directly in the Common Intermediate language? I
>>>>>>>>>>> need to optimize a critical real-time function.
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>
>


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