On Apr 13 12:29, Brian Inglis wrote:
> On 2018-04-13 08:12, L A Walsh wrote:
> > Achim Gratz wrote:
> >> The problem here is that on Linux you don't need to do anything extra to
> >> use any of the advertised logical processors from a single application,
> >> while on Windows you need to first create a thread and set it's affinity to
> >> a different group than where your process was started in, then assign each
> >> new thread an affinity to one of the available groups. If you don't do
> >> that, all threads will be restricted to the original group.
> > Not exactly true. They are not *restricted* -- it's a *feature* of the
> > Windows scheduler, in that future procs/threads inherit the cpu of the
> > parent. Linux's scheduler is more advanced as well as being replaceable.
> > MS
> > doesn't want you to do that
> >> there might need to be some option to restrict Cygwin to a single processor
> >> group for some applications to work (correctly).
> > There is. Start them all on a single cpu & set the cpu mask. Pretty much
> > the same way you restrict procs on linux -- you can run them with a specific
> > cpu mask, and most programs will keep running w/that mask.
> > Unfortunately, AFAIK, I don't think POSIX specifies a way to set affinities,
> > so I'm not sure how cygwin would do it.
>
> Glibc adds {pthread,sched}_...affinity... functions.
> Linux uses namespaces, control groups (cgroups), cpusets, sysfs/kernfs:We would only be able to support it partially. Windows doesn't allow to set thread affinity across CPU groups. There's no simple function to set process CPU group affinity, only a function to set process affinity within a single group. And it has a restriction in that all current threads have to run in the same CPU group. The API is pretty tricky. Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Maintainer cygwin AT cygwin DOT com Red Hat
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