Power6 vs. Power7 hardware performance Post: 302642847

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Operating Systems AIX Power6 vs. Power7 hardware performance Post 302642847 by bakunin on Friday 18th of May 2012 05:56:34 AM

05-18-2012

Registered User

Quote:

Originally Posted by gito

A lot of people realized that if you are calculating performance per core Power7 are slower then Power6.

Sorry to say this, but you should get your wording right: you are confusing speed with performance. This is the reason why even synthetical measurements of CPU performance come in several different numbers instead of some "grand total": there is SPECint, SPECfp, etc., etc. Even then this is not the whole picture when you try to determine how fast the work you want to be done is in fact done: there is L1-, L2- and L3-cache with certain I/O-bandwidth and cache hit-/miss-ratios, there is memory interface bandwidth, there are (a certain number of) pipelines, speculative execution, out-of-order execution, etc., etc.. All these are affecting how fast a program becomes executed, depending on how well a certain program makes use of these various things. And this is only the processor - not to mention the various other devices which affect the working of a system.

To say "processor A is slower than processor B" is like saying "green is better than yellow" - without a frame of reference detailing in which regard it means nothing. It might be that green is better suited for your purpose than yellow, but without stating this purpose in detail you haven't said anything at all.

To come back to the thread-O/Ps problem: without detailed information about the two systems and some way of making them comparable there is no way to say anything meaningful. You said that the two systems have different OS versions, different application versions and (so i do suppose) they differ in some other respects too. It might be that the different processors are the reason, it might as well be something else or a mixture of many factors. There is simply not enough data to base any assumption on.

I hope this helps.

bakunin

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psradm(8)						      System Manager's Manual							 psradm(8)

NAME

       psradm, offline, online - Stops and starts processors in a multiprocessor system

SYNOPSIS

       /usr/sbin/psradm -f  [-v] [[-a] [processor_id...]]

       /usr/sbin/psradm -n  [-v] [[-a] [processor_id...]]

       /usr/sbin/online [-v] [processor_id...]

       /usr/sbin/offline [-v] [processor_id...]

OPTIONS

       The following options apply only to the psradm command: Specifies that all the processors except the master processor be put off line or on
       line.  Puts the specified processor off line.  Puts the specified processor on line.

       The following option applies to all forms of the command: Displays a message about the status of the operation performed on each processor.

DESCRIPTION

       On a multiprocessor system, the psradm command puts one or more processors off line (stops a processor) or on line (starts a processor).

       The processor_id variable specifies an integer that uniquely identifies a processor.  Use the psrinfo command to display processor  identi-
       fication numbers.

       The  offline  command puts one or more processors off line (stops a processor).	If no processors are specified, all processors that are on
       line are stopped except the master processor.

       The online command puts one or more processors on line (starts a processor).  If no processors are specified, all processors that  are  off
       line are started.

       Note that you cannot use these commands to start or stop the master processor in a multiprocessor system.

       You must be the root user to use this command.

       The /var/adm/wtmp file contains information about successful processor state transitions.

RESTRICTION

       Do not use the psradm command to disable CPUs when benchmarking performance, because the command does not provide an accurate reflection of
       the performance of a system that actually has fewer CPUs.  Accurate performance results are obtained only when you disable the CPUs at  the
       SRM console command level.

EXAMPLES

       The  following command puts processors 2 and 3 off line: # psradm -f 2 3 The following command puts all the processors on line: # psradm -n
       -a The following command puts all processors on line: # online -v

FILES

SEE ALSO

       Commands: pset_info(1), psrinfo(1)

       Files: processor_sets(4)

																	 psradm(8)