>From zLinux, I am seeing one CPU at 15%, the other at a much lower value (~5%) using 'mpstat -P ALL'
James Chaplin Systems Programmer, MVS, zVM & zLinux Base Technologies, Inc (703) 921-6220 -----Original Message----- From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On Behalf Of Kim Goldenberg Sent: Thursday, June 12, 2008 3:19 PM To: LINUX-390@VM.MARIST.EDU Subject: Re: Measuring CPU performance? Which is right? Malcolm Beattie wrote: > CHAPLIN, JAMES (CTR) writes: >> On the zLinux guest (ZP013), using sar I get a CPU usage of about 15%: > [...] >> But under Perfkit (zVM) we get the following exception message, 33.5% >> CPU: >> >> 11:51:51 FCXUSL317A User ZP013 %CPU 33.5 exceeded threshold 30.0 for 5 >> min. > [...] >> We have two >> IFLs defined to the guest. > [...] >> Why are the numbers from PERFKIT different from the zLinux environment? > > PerfKit percentages are calculated as "percentage of one engine". > Linux percentages calculate "percentage of CPU resource available to > the image". For your Linux guest with 2 engines, Linux tells you it's > using ~15% of its 2-engines'-worth. PerfKit spells that as ~30% of > a nominally-100%-utilised single engine. Same resource usage, > different way of displaying the measurement. Isn't that in the wrong direction? I'd expect 15% of two engines ~= 7.5% of one engine (.15x200 = .075x100). If, however, Linux is reporting as if 1 engine and PerfKit is doubling due to two engines, I could see your scenario. Which is correct? TIA Kim ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
