On 9/2/2023 12:59, Brian Inglis wrote:
On 2023-09-02 12:27, jeff via Cygwin wrote:
On 9/2/2023 10:56, Brian Inglis wrote:
On 2023-09-02 08:57, jeff via Cygwin wrote:
I have a program that is embarrassing parallel.
On my older computer which has an epyc 7302 (16 cores, 32 threads)
it scales very well using cygwin, and fully utilized all threads.
On my new computer which has an epyc 7B13 (64 cores, 128 threads)
it does not scale very well.
According to the windows task manager, it only uses 74% of the cpu
resources.
The time it takes the program to run on windows is 166 seconds.
Using the same hardware on a recent version of linux, I can get
100% cpu utilization and the program takes 100 seconds to run.
I suspect there may be something in cygwin that doesn't scale well
with lots of posix threads.
Both Windows and Cygwin support multiple processor groups, as some
developers, maintainers, and users need support on such systems, and
the process and thread support has been added to Cygwin.
I know this is a bit of an unusual situation, but you can buy a 128
core / 256 thread system now.
Enclosed is the output of cygcheck.
I updated my version of cygwin to be current as of today, Sep 2 2023.
What Windows edition and version are you running?
For details run:
$ reg query "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows
NT\CurrentVersion" \
| sed '/^\s\+\.*\s/!d;/^.\{80,\}/d'
Some retail editions limit you to 64 threads and that seems to be
your case:
NUMBER_OF_PROCESSORS = '64'
To make full use of your processors, you may have to upgrade your
Windows to a commercial licence (and installation) of Windows 10/11
Pro for Workstations, enabling server features on non-server
"Worskations" ~ HEDTs (High-End DeskTops); see:
https://www.anandtech.com/show/15483/amd-threadripper-3990x-review/3
or just run Linux!
Watch out for terms misused like processor == socket on some sites!
Also, you have to consider these are server systems, mainly designed
for VM not HPC (High Performance Computing) parallelism.
Your older system has higher base and boost/turbo clocks 3.0-3.3GHz:
your newer system has lower clocks 2.25-2.65/3/3.5GHz which seems to
depend on OEM target.
You may also need to upgrade your memory, as each core could run
~10GB/s instructions, and these workstations are often provisioned
with 128-256GB (2-4GB/core), so that may also need a Windows edition
upgrade.
I am running windows 10 professional. Using the task manager, 64
cores and 128 threads shows up for my processor.
As the linked AnandTech article shows and explains with Task Manager/
Performance tab, Win 10 Pro may think you have dual sockets, that
limits the maximum thread parallelism you can achieve:
According to the task manager, it says 'Sockets: 1'.
jeff
--
Problem reports: https://cygwin.com/problems.html
FAQ: https://cygwin.com/faq/
Documentation: https://cygwin.com/docs.html
Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple
