On Mon, Sep 07, 2009 at 04:51:10PM -0500, Ron Johnson wrote: > On 2009-09-07 16:31, ChadDavis wrote: >> I'm using the gnome-system-monitor to watch some apps and their >> resource usage. On the process view, it lists a %CPU column. I >> assume this means the percentage of the CPU that the application is >> currently using. THe documentation doesn't really clarify this, but >> seems not to contradict this interpretation. >> >> The app I'm watching frequently hits 40-60 percent CPU usage. My >> question is about interpreting this. I'm testing on a Core2 Duo >> machine. My understanding of computer architecture is not great, but >> not trivial. Here's what I'm thinking. If one cpu is idle, and an >> app gets to run, it's going to get 100% of the cpu, correct? Even if >> it's only executing a 100 instructions, if there's no contention for >> the CPU, the app will have 100% of the CPU for however small of an >> interval it takes to execute those instructions, correct? I'm >> certainly not familiar with the linux internals of my debian system >> enough > > *When it's running*, it gets 100% of a CPU. > > But on a multiprocessing, multiuser computer, where other processes and > the OS are competing for time, your app only gets full use of the CPU for > a few milliseconds and then the OS takes it away and gives it to another > process. Also, when your app is waiting on IO (from disk, network, > keyboard, etc) it's not doing anything. > > So, that 40-60% seems right. > > If you want to see the CPU burn, try this simple Python script: > > ### BEGIN > i = -2 * 10**9
Why this strange value? > while 1: i = i + 1 > > ### END > > (Note the extra <Enter> you must press after the 2nd line!) Any simple endless loop will do. E.g. the floolwing in the shell: while :; do :; done Note that it makes the shell itself the hog process. -- Tzafrir Cohen | tzaf...@jabber.org | VIM is http://tzafrir.org.il | | a Mutt's tzaf...@cohens.org.il | | best ICQ# 16849754 | | friend -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
