Hi folks,
Brian Inglis via Cygwin wrote:
On 2023-09-02 12:27, jeff via Cygwin wrote:
[...]
When I run cinebench, I can get to 100% cpu utulization (at around 3ghz) on
windows.
Chances are the benchmark is designed to handle that:
"When the program is running inside the group, unless it is processor group aware,
then it can only access other threads in the same group. This means that if a
multi-threaded program can use 128 threads, if it isn’t built with processor
groups in mind, then it might only spawn with access to 64."
I also do not know how you would program for that in Cygwin to map onto the
equivalent Windows function required.
Perhaps one of the developers involved could comment here?
Cygwin doesn't know (at user level) about processor groups as that's a Windows
construct. Cygwin does know about processor affinity and treats all available
processors as a contiguous set, like Linux does, up to 1024 in size. One uses
'taskset' from the util-linux package to assign processes to specific processor(s).
One can deal with thread affinity using pthread_get_affinity_np() and
pthread_set_affinity_np() functions provided by the Cygwin DLL. These are modeled
after the same-named functions in Linux. The internals of these functions do have
to work within the Windows processor group constraints, so not all plausible
set-affinity operations are allowed by Windows. Briefly, you can't move a thread
outside the processor group it's currently in; you have to move its process to the
new group first.
HTH,
..mark
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