Run a Cygwin process with "higher" scheduler priority

[Brian Inglis]

On 2023-08-11 09:44, Cedric Blancher via Cygwin wrote:
> How can we set the scheduler priority for a Cygwin process to "higher"
> than normal on start?
> 
> Basically we want a Cygwin compatible script version of the Windows
> task manager feature Name/PID--->Details--->Set priority--->Higher

Pretend the system is BSD or Linux and web search e.g. SO for that capability, 
facility, or feature, then check Cygwin with Search Packages or:

$ cygcheck -p usr/bin/nice
Found 6 matches for usr/bin/nice
coreutils-debuginfo-8.26-2 - coreutils-debuginfo: Debug info for coreutils
...
coreutils-9.0-1 - coreutils: GNU core utilities (includes fileutils, sh-utils 
and textutils)
$ cygcheck -p usr/bin/renice
Found 6 matches for usr/bin/renice
util-linux-debuginfo-2.32.1-1 - util-linux-debuginfo: Debug info for util-linux
util-linux-debuginfo-2.33.1-1 - util-linux-debuginfo: Debug info for util-linux
util-linux-debuginfo-2.33.1-2 - util-linux-debuginfo: Debug info for util-linux
util-linux-2.32.1-1 - util-linux: Collection of basic system utilities
util-linux-2.33.1-1 - util-linux: Collection of basic system utilities
util-linux-2.33.1-2 - util-linux: Collection of basic system utilities
$ cygcheck -p usr/bin/chrt
Found 2 matches for usr/bin/chrt
util-linux-debuginfo-2.33.1-2 - util-linux-debuginfo: Debug info for util-linux
util-linux-2.33.1-2 - util-linux: Collection of basic system utilities
$ cygcheck -p usr/bin/taskset
Found 2 matches for usr/bin/taskset
util-linux-debuginfo-2.33.1-2 - util-linux-debuginfo: Debug info for util-linux
util-linux-2.33.1-2 - util-linux: Collection of basic system utilities

so you may need to install util-linux (coreutils is already installed as a base 
package for Cygwin) then:

	$ man nice renice taskset chrt

You may need to run these from an elevated admin shell for other user ids, 
unowned processes, or higher (negative) priority.

It has been years since I tried these so can no longer remember if -20 
corresponds to Windows "RealTime" or if you need to use PowerShell to set that e.g.

	$proc	= Get-Process -ProcessName "..."
	$proc.PriorityClass	= "RealTime"

and that needs to be done from an elevated admin (Power)Shell.

Of course, never set that on any system except on a very idle, very I/O bound, 
well tested process, such as ntpd, that needs stably fast interrupt service and 
non-preemptible cpu access for ms every few seconds, preferably on a single or 
few cpus to which affinity is set.

-- 
Take care. Thanks, Brian Inglis              Calgary, Alberta, Canada

La perfection est atteinte                   Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter  not when there is no more to add
mais lorsqu'il n'y a plus rien à retirer     but when there is no more to cut
                                 -- Antoine de Saint-Exupéry