[vtk-developers] Multithreading with Win32 threads

[Pavel Pokutnev]

Thanks for the explanation.

I have tested VTK (just some image filters) with VTK_MAX_THREADS = 16
on new Xeons without any problems.
Is it possible, that someone with git access would change the
VTK_MAX_THREADS to 32, so the community can test it on different
plattforms? Also it would help to verify if there is any issues with
hyper-threading enabled.

Best regard,
Pavel


2011/1/24 David Cole <david.cole at kitware.com>:
> It appears to be used as a "lazy man's" thread local storage in
> vtkMultiThreader (and a couple other scattered uses) -- there are simply
> many arrays of length VTK_MAX_THREADS stored inside an instance of
> vtkMultiThreader. Which could certainly be changed to a single array of
> stuff, and probably even one that's dynamically allocated so that
> VTK_MAX_THREADS is actually unnecessary.
>
> But..... unless somebody goes through and eliminates VTK_MAX_THREADS usage
> (also a valid option, if one is ambitious enough and has sufficient
> time...), then we need an increased "hard coded" value for now.
>
>
> 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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>>
>>    ****      Kenneth Moreland
>>     ***      Sandia National Laboratories
>> ***********
>> *** *** ***  email: kmorel at sandia.gov
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