On Fri, 10 Feb 2012 17:14:44 Basil Chupin wrote:
On 10/02/12 03:21, Adam Tauno Williams wrote:
On Thu, 2012-02-09 at 16:36 +1100, Basil Chupin wrote:
I thought that I would be really smart earlier today and decided (which I have never done before) to open an RSS feed in "All Tabs" in Firefox 10.0. As a result there were something like 250+ tabs opened. I then ran the System Monitor to see how much RAM I was using. 1.4GB. OK. No hassles. 2.6GB left. But then I looked at the cpu usage. It showed that I was using around 1,705% of cpu. Repeat, 1,705% of cpu. Now, I ask you, this is an AMD 32-bit, single core, AMD Athlon XP 3200+.
Because the number doesn't really mean what you are assuming it means. It is just a metric, useful in relation to itself, higher just means higher, lower means lower, other than that it doesn't actually mean much of anything [it certainly doesn't mean what percentage of your CPUs registers are in use, transistors in use, or "capacity" (whatever that means) is in use]. %-of-CPU is actually a pretty crappy metric. If you are interested in system load pay attention to load-average, a metric that actually has a practical meaning.
Which then makes one wonder why somebody would waste their time in writing a program which gives meaningless crap.
Sorry, I'm actually replying to Adam but I had deleted that mail before I got to this point. Load average is no more useful for determining actual CPU load than % CPU Load. Why? Because the load average is simply a count of the average number of processes in the wait queue of the last minute, 5 minutes and 15 minutes (hence the 3 numbers). The problem is that this does not acutally reflect how many processes are actually waiting because process in "uninterruptible sleep" are counted as well. I only found this out in the last week because I was trying to figure out how my load average could be constantly sitting around or just over 2 when the system was sitting there otherwise idle. Sure enough, there are 2 processess in an uninterruptible sleep state. You can't terminate processes in this state either - the only way to get rid of them is to reboot the machine. Since I usually only do that after a) a power failure, b) going away for a holiday or c) after a kernel update, I guess the load average will be sitting around 2 for a fair while yet. At least now I know why. :-) -- =================================================== Rodney Baker VK5ZTV rodney.baker@iinet.net.au =================================================== -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org