1. IQS2 is an implicit queuing system, in the sense that users do not have to explicitly submit jobs to a queue with commands like qsub or llsubmit.
2. IQS2 is a sort of portable ultrabatch scheduling class, in the sense that processes are still managed by your operating system's usual scheduler, but IQS2 adds an additional layer of scheduling overtop of that, which is extremely coarse-grained (subject to how you configure IQS2).

• IQS2 just lives in the background, polling the process table from time to time. If in doing so, IQS2 notices a program (PID) that is taking a large amount of CPU in a given time interval, IQS2 will add that PID to a round robin list of PID's to manage.
• These selected PID's of high-CPU programs are simply kill -STOP'd and kill -CONT'd over and over, to achieve the effect of only a user defined number of CPU hungry processes running at a time.
• If you have processes that are taking up too much virtual memory, then IQS2 is probably not the right solution for you, though you could consider adding more swap space. This is because IQS2 does not pull stopped processes out of VM - it only pauses them.

Operating system	Support
Linux	Developed and tested on Linux
MacOS	Only lightly tested, but seems to work. psutil supports it, and MacOS appears to have the right signals.
Windows	Untested, and probably won't work. psutil supports it, but Windows doesn't support many signals.

Path	Description	Who/what populates it
/var/IQS	this directory is created automatically by IQS2 if it does not exist	IQS2
/var/IQS/managed	this file is a list of PID's being managed by IQS2, one PID per line	IQS2, sometimes modified by the System Administrator
/var/IQS/exempt-users	this file is a list of usernames whose processes will never be managed by IQS2, one username per line.	The system administrator
/var/IQS/exempt-programs	this file is a list of programs, one per line, that will never be managed by IQS2. It uses a simple substring search. Note that once you enable this for a program, if your users figure out that this has been done, they can be ornery by changing their program's argv somehow to look like one of the exempt programs!. Do not put "ps -ef" or "ps auxww" names in this file; instead run the ./show program in the IQS2 source to identify what name(s) you should use in this file.	The system administrator

Signal	What it's used for in an IQS2 context
SIGCONT	used internally by IQS2 to resume a process
SIGHUP	sent by an administator to IQS2, to make IQS2 reread its list of managed PID's from /var/IQS/managed. Using this facility and a text editor, you can easily add or remove a PID from IQS2's management
SIGINT	sent by an administrator to IQS2, to make IQS2 tell all managed processes to resume, and IQS2 then exits. Because the list of managed PID's is left in /var/IQS/managed, you can conveniently stop and restart IQS2, without IQS2 losing track of which PID's it should be managing.
SIGSTOP	used internally by IQS2 to pause a process
SIGTERM	same as SIGINT

Option	Purpose
-v	Run verbosely
-n x	Run a maximum of x IQS2-managed processes concurrently
--time-slice t	How frequently to check the process table and changes processes in seconds; defaults to 60.0
--fraction f	What fraction of the time slice must be seen before commencing IQS2 management; defaults to 0.18

Condition under which you would give an exemption	The processes' names to exempt in /var/IQS/exempt-programs
If you browse the web on an IQS2 machine	chrome, firefox, etcetera
If you use graphics on an IQS2 machine	Xorg or Wayland (unsure of the Wayland name at this time)
If you do file transfers over sshfs on an IQS2 machine	sshfs and ssh
If you're using IQS2 on a modern Linux system with systemd. This is "init" on most Linux systems today.	systemd
Pretty much always, but especially on a system that swaps a lot	kswapd

You can see what psutil sees a process as using "./show". "show" is like ps -ef, but shows psutil names, not "ps" names.

• $ cd /tmp
• $ svn checkout https://stromberg.dnsalias.org/svn/IQS2/trunk IQS2 # Downloading other ways won't provide the needed external references.
• $ cd IQS2
• $ sudo su # Or just su, depending on how you usually increase privilege
• # make install
• # ./add-to-systemd # Optional, and only suitable for modern Linuxes that have systemd. Not appropriate for MacOS.

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