Messages in this thread | | | From | Denis Vlasenko <> | Subject | Re: CPU utilization and hyperthreading | Date | Sun, 6 Nov 2005 16:26:13 +0200 |
| |
On Sunday 06 November 2005 16:13, erezz@techunix.technion.ac.il wrote: > Hi, > > I'm using a 2.6.4-52 (Suse 9.1 pro distribution) kernel on a 3.2 dual > XEON machine (with hyperthreading). > > I'm trying to analyze the performance of a kernel module that contains > 4 kernel threads (3 of them are more active). Also, some of the work is > done in a tasklet. The CPU load (as shown in vmstat) doesn't reach more > than 50%. When trying to artificially stress the system with some > useless loops, the CPU load reaches 65% (but I cannot reach 100%). Also, the > interrupts count in vmstat is around 20000 (1000 when idle). > > My questions are: > 1. Why can't I reach 100%?
You can.
# while true; do true; done & # while true; do true; done & # while true; do true; done & # while true; do true; done &
> 2. I guess that since I have 4 virtual CPUs (as shown in /proc/cpuinfo), not all > of them are stressed. Is there a way to see the CPU utilization for each CPU > (vmstat doesn't allow that)?
top
> 3. When I load a module with a kernel thread that runs an infinite loop, I get > 25% CPU utilization (50% if I run 2 threads). Is it because I'm using 100% of a > single CPU (out of 4)? > 4. How is the time spent in interrupt context estimated? Is it possible to view > it somehow? -- vda - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |