https://bugzilla.kernel.org/show_bug.cgi?id=3094 --- Comment #28 from Artem S. Tashkinov <t.artem@xxxxxxxxxxxx> 2010-05-20 16:56:48 --- > Load is the average number of threads which are running or willing to run. It > doesn't have much to do with actual cpu usage. Load average can and does go > way above the number of processors. It doesn't mean the kernel is creating > virtual cpus for you. I haven't said anything about creation of virtual CPUs, but I've always thought that one can estimate real system load (it maybe above 100%) by diving load average by number of CPUs and for "normal" tasks like mathematical calculations this principle holds true. E.g. : `cat < /dev/urandom > /dev/null` on all Unixes will result in 1.0 load average. That means that one CPU or CPU core is 100% busy. Run this task twice and you'll get 2.0 load average or for 4 cores system that means half of the CPUs are busy churning random numbers. Why this principle doesn't hold true for tasks which are bound by IO operations is beyond my understanding. Why IO wait time is even included in load average statistics is also beyond my understanding. So, on behalf of almost all Linux users I have to ask this hard question: how one is supposed to understand/interpret top/htop/whatever_else_utility numbers when IDLE time is shown as _0%_ for _all_ IO intensive operations? In OS, everyone hates but most people still use, IO wait time is shown as kernel time but otherwise CPU is mostly _idle_ (90% of more, depending on chipset, IO drivers, etc) - in Linux CPU is _100% busy_ - and it makes no sense, e.g. `cat /dev/sda > /dev/null` will result in top showing: Cpu(s): 4.3%us, 4.0%sy, 0.0%ni, 75.4%id, 15.8%wa, 0.0%hi, 0.5%si, 0.0%st As you can clearly see my 4 CPUs system is approximately 25% busy, i.e. one CPU is 100% busy doing something. So, _please_, fix the kernel, fix top/htop/load_average, fix whatever you want, but, please, stop confusing people with numbers that make no sense. -- Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are watching the assignee of the bug. -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
