[x265] [PATCH] bug: Making windows cpu mask 64-bits

[Pradeep Ramachandran]

On Thu, Sep 17, 2015 at 12:08 AM, Steve Borho <steve at borho.org> wrote:

> On 09/15, Pradeep Ramachandran wrote:
> > # HG changeset patch
> > # User Pradeep Ramachandran <pradeep at multicorewareinc.com>
> > # Date 1442332345 -19800
> > #      Tue Sep 15 21:22:25 2015 +0530
> > # Node ID a103f446053e9992b06e4b522e9fcab62d47ca68
> > # Parent  365f7ed4d89628d49cd6af8d81d4edc01f73ffad
> > bug: Making windows cpu mask 64-bits
> >
> > diff -r 365f7ed4d896 -r a103f446053e source/common/threadpool.cpp
> > --- a/source/common/threadpool.cpp    Tue Sep 08 16:38:01 2015 +0530
> > +++ b/source/common/threadpool.cpp    Tue Sep 15 21:22:25 2015 +0530
> > @@ -473,7 +473,7 @@
> >  void ThreadPool::setThreadNodeAffinity(void *numaMask)
> >  {
> >  #if defined(_WIN32_WINNT) && _WIN32_WINNT >= _WIN32_WINNT_WIN7
> > -    if (SetThreadAffinityMask(GetCurrentThread(),
> (DWORD_PTR)(*((DWORD*)numaMask))))
> > +    if (SetThreadAffinityMask(GetCurrentThread(),
> (DWORD_PTR)(*((DWORD64*)numaMask))))
>
> why the casts at all, isn't this just (DWORD_PTR)numaMask? Or are there
> some crazy little endian pointer tricks being done here?
>
> btw: gotta love Windows data types.. DWORD64? really?


:-)


>
> >          return;
> >      else
> >          x265_log(NULL, X265_LOG_ERROR, "unable to set thread affinity
> for NUMA node mask\n");
> > diff -r 365f7ed4d896 -r a103f446053e source/common/threadpool.h
> > --- a/source/common/threadpool.h      Tue Sep 08 16:38:01 2015 +0530
> > +++ b/source/common/threadpool.h      Tue Sep 15 21:22:25 2015 +0530
> > @@ -85,7 +85,7 @@
> >      int           m_numWorkers;
> >      void*         m_numaMask; // node mask in linux, cpu mask in windows
> >  #if defined(_WIN32_WINNT) && _WIN32_WINNT >= _WIN32_WINNT_WIN7
> > -    DWORD         m_winCpuMask;
> > +    DWORD64       m_winCpuMask;
>
> technically, we're copying bits from GROUP_AFFINITY.Mask, which is
> defined as type KAFFINITY, which appears to be a mirror for a kernel
> variable size. But SetThreadAffinityMask() wants a DWORD_PTR. Honestly,
> these win32 APIs are a mess.
>
> digging around and found this:
>
>
> http://stackoverflow.com/questions/20792975/what-is-the-replacement-for-undocumeneted-windows-kernel-api-kesetaffinitythre
>
> which has no answers. The APIs you really want are only available to
> kernel space code.
>
> I also get the impression that if libx265 is compiled for 32bits,
> m_winCpuMask should be DWORD.  IE: win64 SetThreadAffinityMask() is
> expecting the pointer to reference a DWORD64 but 32bit win32
> SetThreadAffinityMask() is expecting a DWORD32.
>

Looks like DWORD_PTR and KAFFINITY are typedefed from ULONG_PTR. Scroll to
DWORD_PTR in
https://msdn.microsoft.com/en-us/library/windows/desktop/aa383751(v=vs.85).aspx
So moving m_winCpuMask to DWORD_PTR should work


> Hmm.. perhaps we should be using SetThreadGroupAffinity()
>

But we're trying to set a mask as multiple numa nodes may be selected.

Pradeep.


>
> --
> Steve Borho
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> x265-devel at videolan.org
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