Oh, duh. This server seems to have 4 vcpus. I assumed 2 since most here are 2. Thank you Rob for the memory stick to the head.
Marcy -----Original Message----- From: Linux on 390 Port [mailto:[email protected]] On Behalf Of Rob van der Heij Sent: Wednesday, February 18, 2015 11:29 PM To: [email protected] Subject: Re: [LINUX-390] vmstat just plain wrong? On 18 February 2015 at 23:49, Marcy Cortes <[email protected]> wrote: > SUSE 11 SP3 - pretty current maintenance, under z/VM 6.3. > > Has anyone else see where vmstat severely under reports CPU usage? > > I'll report it if this is not a known problem. > > Linux would only report *virtual* time, not any CP overhead. There's also a tiny portion of virtual time lost every time Linux gets dispatched. When a polling process is doing 100,000 per second, those tiny portions add up. You would compare things on ESALNXV mainly to see this. And if it's a virtual-MP, be aware the vmstat normalizes to 100% max and rounds to full percents. And I would need to double check what's happending when the vmstat samples get skewed a lot (so your "vmstat 10" takes much more than 10 seconds per round). One would expect it to divide by elapsed time, but the elongation might be at some particular place in the code. You know I'd be more happy to look at the data and see what can be explained from it. Rob van der Heij http://www.velocitysoftware.com/ ---------------------------------------------------------------------- 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 more information on Linux on System z, visit http://wiki.linuxvm.org/ ---------------------------------------------------------------------- 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 more information on Linux on System z, visit http://wiki.linuxvm.org/
