From: Martin Turgeon [mailto:free...@optiksecurite.com] To: freebsd-questions@freebsd.org Sent: Thu, 14 Oct 2010 21:46:13 +0200 Subject: How is CPU usage calculated?
Hi list! I did a strange observation yesterday night. The CPU usage reported by top doesn't match what is indicated under it. I was seeing around 80-90% user, 5% system, 1% interrupt and 10% idle. But the process details under it doesn't match. mysqld was taking around 250% (WCPU) with a few httpd processes at 1-2%. The system is running GENERIC 8.0-REL on a Xeon E5630 (quad core with hyperthreading so 8 CPUs). MySQL and Apache each have their own jail (I don't think it will matter but just in case) I understand why the mysqld process take more than 100% but how can I know what's taking the rest? Why doesn't the total user CPU usage match the total of the CPU usage of each process? Is there a link with hyperthreading? There sure is a logical answer and I would really like to know it :) Yes if you have multiple cpu's, cores or hyperthreading than each unit can be used up to 100% Mysql has multiple threads, you can check with top -P to see the multiple cores and when top is running give the command H (capital H) to see the threads of each process DISCLAIMER: This e-mail is for the intended recipient(s) only. Access, disclosure, copying, distribution or reliance on any of it by anyone else is prohibited. If you have received it by mistake please let us know by reply and then delete it from your system. _______________________________________________ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "freebsd-questions-unsubscr...@freebsd.org"
