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# ionice and nice notes #
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# nice -n19 is nicest on CPU priority
# ionice -c2 -n7 is nicest on IO priority also so is ionice -c3. ionice -c3 is probably nicer.

nice -n19 PROGRAMNAME # starts a program nice (on cpu)

ionice -c2 -n7 PROGRAMNAME # starts a program nice (on io)
ionice -c3 PROGRAMNAME # starts a program nice (on io)

# *** BOTH **** How to ionice and nice at same time
ionice -c2 -n7 nice -n19 PROGRAMNAME # starts a program running really nice & ionice (cpu and io)
ionice -c3 nice -n19 PROGRAMNAME # starts a program running really nice & ionice (cpu and io)

renice -n19 PID # If a program is already running use this method to make it nice, you can make it nice with "renice". First find the PID of the program.
# syntax of renice might differ. space after -n and require -p for PID. "renice -n PRIO -p PID"
renice -n 19 -p PID 

ionice -c2 -n7 -p PID # you can re-ionice/reionice using ionice, the same program deals with already running programs and new programs about to run

ionice -c3 -p PID # you can re-ionice/reionice using ionice, the same program deals with already running programs and new programs about to run

# cant renice and re-ionice at same time, just string them in once command with ";", like this: "renice -n19 PID; ionice -c3 PID"

### To run a couple programs nice ###

nice -n19 /bin/bash -c "program1; program2;"
ionice -c2 -n7 /bin/bash -c "program1; program2;"
ionice -c2 -n7 nice -n19 /bin/bash -c "program1; program2;"
ionice -c3 nice -n19 /bin/bash -c "program1; program2;"

# note can replace bash with /bin/bash with /bin/sh if thats your shell (usually /bin/sh will point to the correct shell of choice). Find out your shell with "echo $SHELL"

# Or if you want them to run at the same time. Change the ; to &, but make sure to have spaces

nice -n19 /bin/bash -c "program1 & program2 &"
ionice -c2 -n7 /bin/bash -c "program1 & program2 &"
ionice -c2 -n7 nice -n19 /bin/bash -c "program1 & program2 &"
ionice -c3 nice -n19 /bin/bash -c "program1 & program2 &"

### QUICK NOTES ON nice ###

# nice -n0 is default, nice -n19 is lowest cpu priority (-20 is highest priority on cpu, 0 is default, 19 is loweest)

* nice of "nice -n19" is the nicest a program can run, therefore it will have lower priority on the CPU and free up CPU time.

### QUICK NOTES ON ionice ###

# http://www.linux-commands-examples.com/ionice

# ionice -c1 realtime : highest priority
# ionice -c2 best effort : average priority and can set a sub priority with -n0 to -n7 (0 is highest priority for -c2, and 7 is lowest priority for -c2)
# ionice -c3 idle L this is lowest priority (even lower then -c2 -n7, and it only gets access when the disk is idle and no other program is accessing the disk)

# ionice -c1 (highest priority) also ionice -c2 -n0 is high priority (but -c1 is higher)
# note with -c1 & -c3 you cant set subpriority but with -c2 you can

# ionice -c2 -n7 (lowest priority)
# with -c2 you can set sub priority 0 highest, 7 lowest (the numbers are switched dont get confused)
# c2 is best effort and now we can set priority 0 to 7 where 0 is highest and 7 is lowest priority to the disk

# ionice -c3 (will only let program run when nothing is accessing disk for long time, so it will only let it run when its idleing)

* ionice of "ionice -c2 -n7" and "ionice -c3" are the nicest on IO a program can run. Meaning it will have lower priority, giving more to other processes.