[PATCH v2] Cygwin: Carry process affinity through to result

[Corinna Vinschen]

On Mar 18 00:53, Mark Geisert wrote:
> Due to deficient testing, the current code doesn't return a valid result
> to users of sched_getaffinity().  The updated code carries the determined
> procmask through to the generation of result cpu mask.
> 
> Recognize Windows' limitation that if the process is multi-group (i.e.,
> has threads in multiple cpu groups) there is no visibility to which
> processors in other groups are being used.  One could remedy this by
> looping through all the process' threads, but that could be expensive
> so is left for future contemplation.  In addition, we'd have to maintain
> our own copy of each thread's current group and mask in internal overhead.
> (By the way, multi-group processes are only possible on Windows systems
> with more than 64 hardware threads.)
> 
> A release note for 3.6.0 is included.
> 
> Reported-by: Christian Franke <Christian.Franke@t-online.de>
> Addresses: https://cygwin.com/pipermail/cygwin/2025-March/257616.html
> Signed-off-by: Mark Geisert <mark@maxrnd.com>
> Fixes: 641ecb07533e ("Cygwin: Implement sched_[gs]etaffinity()")
> 
> ---
>  winsup/cygwin/release/3.6.0 |  4 ++++
>  winsup/cygwin/sched.cc      | 11 +++++++++--
>  2 files changed, 13 insertions(+), 2 deletions(-)

Pushed.


Thanks,
Corinna