llvm dev - Sep 2014 - [LLVMdev] [lldb-dev] RFC: LLVM should require a working C++11 <thread>, <mutex>, and <atomic>

Hi,
I think I can at least answer why the Rust project prefers to use
mingw-w64-win32threads:
1. It does not inject dependency on libwinpthread.dll, which is nice.
2. Those who tried building LLVM with mingw-w64-pthreads, had reported
significant slowdown of the resulting Rust compiler (as compared to one
linked to LLVM compiled with the win32threads flavor).   Profiling seemed
to point towards libpthreads' implementation of mutex.  I had checked the
source, and indeed, it looked not very efficient (
http://sourceforge.net/p/mingw-w64/bugs/344).  It would be nice to get a
second opinion, though, maybe I missed something.

Vadim


On Wed, Sep 24, 2014 at 10:55 AM, Chandler Carruth <chandlerc at
google.com>
wrote:
>
> On Wed, Sep 24, 2014 at 10:37 AM, Óscar Fuentes <ofv at wanadoo.es>
wrote:
>
>> The best thing for understanding their reasons is to ask them to speak
>> up.
>>
>
> I asked them directly, and this thread is a chance for them to speak up
> again. I *think* I've addressed the concerns of those I've spoken
to
> directly, but there may be other folks or other concerns or I may have
> messed it up. =]
>
>
>> My experience on the MinGW/MinGW-w64 communities is that those who
>> choose MinGW is because of ignorance about MinGW-w64 and because there
>> are lots of documents on the 'net that references MinGW. MinGW is,
to
>> all practical effects, a zombie project and there is no reason to
prefer
>> it over MinGW-w64 nowadays.
>>
>
> :: shrug ::
>
> I'm not such a user, and so I don't want to speculate as to what
motivates
> them.
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
>
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Vadim,

Thanks for the feedback on the -win32. A dependency on a small DLL with BSD
license does not sound too bad, but performance regression is obviously a
serious problem.

However, by disabling <mutex> use with -pthreads rust performance should
be
same as -win32 threads?
Saying it another way, does the -win32 version have any feature that
-pthreads vesion do not have?

Yaron


2014-09-25 9:52 GMT+03:00 Vadim Chugunov <vadimcn at gmail.com>:
> Hi,
> I think I can at least answer why the Rust project prefers to use
> mingw-w64-win32threads:
> 1. It does not inject dependency on libwinpthread.dll, which is nice.
> 2. Those who tried building LLVM with mingw-w64-pthreads, had reported
> significant slowdown of the resulting Rust compiler (as compared to one
> linked to LLVM compiled with the win32threads flavor).   Profiling seemed
> to point towards libpthreads' implementation of mutex.  I had checked
the
> source, and indeed, it looked not very efficient (
> http://sourceforge.net/p/mingw-w64/bugs/344).  It would be nice to get a
> second opinion, though, maybe I missed something.
>
> Vadim
>
>
> On Wed, Sep 24, 2014 at 10:55 AM, Chandler Carruth <chandlerc at
google.com>
> wrote:
>
>>
>> On Wed, Sep 24, 2014 at 10:37 AM, Óscar Fuentes <ofv at
wanadoo.es> wrote:
>>
>>> The best thing for understanding their reasons is to ask them to
speak
>>> up.
>>>
>>
>> I asked them directly, and this thread is a chance for them to speak up
>> again. I *think* I've addressed the concerns of those I've
spoken to
>> directly, but there may be other folks or other concerns or I may have
>> messed it up. =]
>>
>>
>>> My experience on the MinGW/MinGW-w64 communities is that those who
>>> choose MinGW is because of ignorance about MinGW-w64 and because
there
>>> are lots of documents on the 'net that references MinGW. MinGW
is, to
>>> all practical effects, a zombie project and there is no reason to
prefer
>>> it over MinGW-w64 nowadays.
>>>
>>
>> :: shrug ::
>>
>> I'm not such a user, and so I don't want to speculate as to
what
>> motivates them.
>>
>> _______________________________________________
>> LLVM Developers mailing list
>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
>>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
>
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Hi Yaron,
Not sure I understand your question.  Wasn't <mutex> one of the more
important C++11 features that LLVM would like to use?

On Thu, Sep 25, 2014 at 1:24 AM, Yaron Keren <yaron.keren at gmail.com>
wrote:
> Vadim,
>
> Thanks for the feedback on the -win32. A dependency on a small DLL with
> BSD license does not sound too bad, but performance regression is obviously
> a serious problem.
>
> However, by disabling <mutex> use with -pthreads rust performance
should
> be same as -win32 threads?
> Saying it another way, does the -win32 version have any feature that
> -pthreads vesion do not have?
>
> Yaron
>
>
> 2014-09-25 9:52 GMT+03:00 Vadim Chugunov <vadimcn at gmail.com>:
>
>> Hi,
>> I think I can at least answer why the Rust project prefers to use
>> mingw-w64-win32threads:
>> 1. It does not inject dependency on libwinpthread.dll, which is nice.
>> 2. Those who tried building LLVM with mingw-w64-pthreads, had reported
>> significant slowdown of the resulting Rust compiler (as compared to one
>> linked to LLVM compiled with the win32threads flavor).   Profiling
seemed
>> to point towards libpthreads' implementation of mutex.  I had
checked the
>> source, and indeed, it looked not very efficient (
>> http://sourceforge.net/p/mingw-w64/bugs/344).  It would be nice to get
a
>> second opinion, though, maybe I missed something.
>>
>> Vadim
>>
>>
>> On Wed, Sep 24, 2014 at 10:55 AM, Chandler Carruth <chandlerc at
google.com>
>> wrote:
>>
>>>
>>> On Wed, Sep 24, 2014 at 10:37 AM, Óscar Fuentes <ofv at
wanadoo.es> wrote:
>>>
>>>> The best thing for understanding their reasons is to ask them
to speak
>>>> up.
>>>>
>>>
>>> I asked them directly, and this thread is a chance for them to
speak up
>>> again. I *think* I've addressed the concerns of those I've
spoken to
>>> directly, but there may be other folks or other concerns or I may
have
>>> messed it up. =]
>>>
>>>
>>>> My experience on the MinGW/MinGW-w64 communities is that those
who
>>>> choose MinGW is because of ignorance about MinGW-w64 and
because there
>>>> are lots of documents on the 'net that references MinGW.
MinGW is, to
>>>> all practical effects, a zombie project and there is no reason
to prefer
>>>> it over MinGW-w64 nowadays.
>>>>
>>>
>>> :: shrug ::
>>>
>>> I'm not such a user, and so I don't want to speculate as to
what
>>> motivates them.
>>>
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>
>>>
>>
>> _______________________________________________
>> LLVM Developers mailing list
>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
>>
>
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