For 2023 - we are now fully retired from IT training.
We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.
Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!
I am also active in many other area and still look after a lot of web sites - you can find an index ((here))
Linux / Unix - process priority and nice
(written 2007-01-10, updated 2007-01-11)
|Visit certain theme parks, stand in queues for the rides. OK - that's fair enough at time. But then see folks with "fast pass" special tickets go the front and get, more or less, straight on. You may have seen the scenario ....|
But look carefully, and the operators never let the whole of the fast-track bunch through at once. If there's a queue there too, they'll clear it rapidly, but still keep a modicum of flow running from the main lines.
|A similar thing happens with Linux / Unix tasks that are awaiting the processor - known as "runnable"s. There's a concept known as "niceness". Default value 0 - standard queue. Positive value - a process that is nice to others and hold back, so lower priority. And a negative value - a process that barges in and gets higher priority treatment. |
But there's NOT an absolute rule that runnables are started are run without limit in the order "least nice first" - there has to be some sharing and although the higher priority processes will be kept waiting far less, they will be kept waiting on occasions.
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articlesA164 - Web Application Deployment - Services and Regular Jobs 
Repeating tasks with crontab - (2005-12-27) 
Browser -> httpd -> Tomcat -> MySQL. Restarting. - (2006-10-28) 
Linux run states, shell special commands, and directory structures - (2007-08-03) 
Automatic startup and shutdown of Tomcat - (2008-02-24) 
Changing a screen saver from a web page (PHP, Perl, OSX) - (2008-05-06) 
FTP server on Fedora Linux - (2008-07-06) 
Apache httpd, MySQL, PHP - installation procedure - (2008-08-01) 
memcached - overview, installation, example of use in PHP - (2008-08-02) 
Dialects of English and Unix - (2008-08-21) 
daemons - what is running on my Linux server? - (2008-11-23) 
Using the internet to remotely check for power failure at home (PHP) - (2009-04-29) 
What Linux run level am I in? - (2009-05-15) 
What are .pid files? - (2010-10-23) 
On time - (2011-01-23) 
The Kernel, Shells and Daemons. Greek Gods in computing - (2012-07-01) 
Managing daemons from a terminal session - (2012-07-01) 
Starting MySQL. ERROR! The server quit without updating PID file - how we fixed it. - (2015-05-06)
Some other Articles
Chronic fatigue help - a new discussion forumrobots.txt - a clue to hidden pages?Hotel for TrowbridgeOur search engine placement is dropping.Linux / Unix - process priority and niceCue the music, I'm happy.The Wheatsheaf 2, The Bell 0Tomorrow's keywords - London, Training, Course, PHP, Ruby.Web site - a refresh to improve navigationFinding public writeable things on your linux file system
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