While you are compiling packages and at the same time you are working with your box, probably you’ll notice the machine is less responsive than usual. Although this in principle is not necessarly an abnormal behaviour it could be very annoying.
To diminish the impact of such situation, you could reduce the priority that the kernel assigns to emerge.
Portage provides a configuration parameter that allows you to control this priority. Edit /etc/make.conf and add the following:
This will pass “17″ as value to the nice command. Possible values range from “-20″ to “20″, being “-20″ the highest priority and “20″ the lowest. 0 is standard or normal priority.
See nice man page for more info.