On Wednesday, 02/17/2010 at 10:35 EST, Martin Schwidefsky <[email protected]> wrote: > On Wed, 17 Feb 2010 08:18:12 -0600 > "Shedlock, George" <[email protected]> wrote: > > > If the selection of the CPU capability is incorrect, what exactly does that > > mean to the kernel? Does that mean that linux has been running at the speed > > of the GP processors? > > No, an IFL always runs at its native speed. Only the number that is supposed to > detail the processor speed is wrong.
Careful! The Primary and Secondary CPU capabilities of the machine, obtained from stsi(1,2,2), must be modified by the Capability Adjustment Factors from stsi(2,2,2) and stsi(3,2,2), using stsi(0,0,0) as a guide. If Linux is running on an IFL, then the Secondary capability is relevant. If it is running on a GP, then Primary is the number to watch. In a z/VM-mode LPAR, it gets strange since z/VM can simulate an IFL on a GP (but not vice versa), but the values from STSI are not affected (i.e. reversed). If it's going to report it at all, Linux should report both primary and secondary capability. It's up to the person issuing the command to know which number is correct based on the real machine, LPAR, and virtual machine configuration. All that said, the number isn't terribly interesting except to compare to other machines and models, and other CPUs on the same machine. E.g. If you have 1000 on machine #1 and 500 on machine #2, then machine #2 has twice the capability of machine #1. If the capability of the machine changes, so do these values. Oh, and folks should be warned not to conflate "capability" with "capacity." The former is based on configuration and is a constant (for various values of 'constant'.) The latter has as a major component, "it depends." Alan Altmark z/VM Development IBM Endicott ---------------------------------------------------------------------- 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
