[vtk-developers] Multithreading with Win32 threads

David Cole david.cole at kitware.com
Tue Jan 25 14:41:03 EST 2011


I'm not going to object, but .... vtkMultiThreader contains *several*
arrays that are based on the value here. Do a quick sanity test of
creating a vtkMultiThreader object and inspecting its size. Just make
sure it's not ridiculously large.

Perhaps adding a CMake value that can be tweaked to taste (and then
configured into vtkConfigure.h) with a default value of 32-ish would
be more reasonable.


On Tue, Jan 25, 2011 at 2:11 PM, David Partyka
<david.partyka at kitware.com> wrote:
> I am going to change it to 1024 unless someone objects for the immediate
> term. And then from there switch it to be dynamic and deprecate
> VTK_MAX_THREAD entirely.
>
> On Tue, Jan 25, 2011 at 8:27 AM, David Partyka <david.partyka at kitware.com>
> wrote:
>>
>> I definitely agree but this looks like it should be given
>> a deprecation cycle as it involves removing API, there are set/get macros
>> and VTK_MAX_THREAD is a const in a global header. Though, nearly all of the
>> usage of VTK_MAX_THREAD is in vtkMultiThreader and it definitely would not
>> be hard to switch it to dynamically store threads.
>> That said, I can check in a much larger value for VTK_MAX_THREAD right
>> now. How about 128? 256? 1024? INT_MAX?
>> After that, myself or someone else can switch it to use a vector instead
>> of a fixed size array and then add the deprecation macros so people know
>> it's going away. Does this sound reasonable? Or too cautious? :-p
>>
>> On Tue, Jan 25, 2011 at 8:04 AM, Will Schroeder
>> <will.schroeder at kitware.com> wrote:
>>>
>>> I agree with Ken, IMO we should remove hardcoded limits on threads. In
>>> fact I can see creating some specialized code to determine the "optimal"
>>> number of threads (with provisions for manual override). After all in the
>>> Nat'l Lab world that Ken/Sandia resides in, I've heard the dudes talk about
>>> hundreds or thousands of processes, etc....it's evolving fast and we don't
>>> want to have to keep changing this.
>>> W
>>>
>>>
>>>
>>> On Mon, Jan 24, 2011 at 11:14 AM, Moreland, Kenneth <kmorel at sandia.gov>
>>> wrote:
>>>>
>>>> Why is there a hardcoded maximum in the first place?  It seems to me
>>>> that whatever number you choose now will be excessively high and/or obsolete
>>>> in the coming years as the number of cores per processor grows.
>>>>
>>>> -Ken
>>>>
>>>>
>>>> On 1/24/11 8:04 AM, "Bill Lorensen" <bill.lorensen at gmail.com> wrote:
>>>>
>>>> ITK has had the max set to 128 for quite a while.
>>>>
>>>> On Mon, Jan 24, 2011 at 9:53 AM, David Partyka
>>>> <david.partyka at kitware.com> wrote:
>>>> > Sure thing, especially considering one can get a machine with dual
>>>> > Hexa-cores + Hyper Threading resulting in 24 available cores.
>>>> >
>>>> > On Mon, Jan 24, 2011 at 9:39 AM, David Cole <david.cole at kitware.com>
>>>> > wrote:
>>>> >>
>>>> >> I think it's just old and leftover, and nobody has yet found a
>>>> >> compelling
>>>> >> need for more than 8 threads on Windows. It should be fine to
>>>> >> increase this
>>>> >> number, especially if you actually have a Windows box with more than
>>>> >> 8
>>>> >> processors on it.
>>>> >>
>>>> >> Feel free to change your build locally to increase that value.
>>>> >> Perhaps
>>>> >> somebody here on the VTK developers list is also contemplating more
>>>> >> powerful
>>>> >> Window machines these days... Anybody here want to bump this up and
>>>> >> commit
>>>> >> the change?
>>>> >>
>>>> >>
>>>> >> On Mon, Jan 24, 2011 at 5:11 AM, Pavel Pokutnev
>>>> >> <pavel.pokutnev at googlemail.com> wrote:
>>>> >>>
>>>> >>> Hello vtk-devs,
>>>> >>>
>>>> >>> sorry, but I would like to repeat my question.
>>>> >>> There is a define VTK_MAX_THREADS in "Common/vtkSystemIncludes.h".
>>>> >>> It
>>>> >>> is defined to 8 for Win32 threads, but for all other platforms to
>>>> >>> 32.
>>>> >>> What is the cause for this non-conformity?
>>>> >>>
>>>> >>> Best regards,
>>>> >>> Pavel
>>>> >>> _______________________________________________
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>>>> >>
>>>> >>
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>>>> >>
>>>> >
>>>> >
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>>>>
>>>>
>>>>    ****      Kenneth Moreland
>>>>     ***      Sandia National Laboratories
>>>> ***********
>>>> *** *** ***  email: kmorel at sandia.gov
>>>> **  ***  **  phone: (505) 844-8919
>>>>     ***      web:   http://www.cs.unm.edu/~kmorel
>>>>
>>>>
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>>>
>>>
>>>
>>> --
>>> William J. Schroeder, PhD
>>> Kitware, Inc.
>>> 28 Corporate Drive
>>> Clifton Park, NY 12065
>>> will.schroeder at kitware.com
>>> http://www.kitware.com
>>> (518) 881-4902
>>
>
>
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