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Special Forums UNIX and Linux Applications High Performance Computing IBM Hardware: Test speed of an execution core reliably. Post 302852907 by Corona688 on Thursday 12th of September 2013 03:12:05 PM
Old 09-12-2013
Multithreading does not work that way; two cores can't cooperate to run a single-threaded program faster. Single-threaded programs will run slower on machines with lots of slower cores; we've had some puzzled folks ask us why their new machines have worse single-threaded benchmarks than their old ones.

But more cores means you can run more threads or processes at once without sharing time; more total work can be accomplished in the aggregate; but a program has to be designed with this in mind (or multiple instances of it run) to take advantage of this capability.
 

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hostinfo(8)						    BSD System Manager's Manual 					       hostinfo(8)

NAME
hostinfo -- host information SYNOPSIS
hostinfo DESCRIPTION
The hostinfo command displays information about the host system on which the command is executing. The output includes a kernel version description, processor configuration data, available physical memory, and various scheduling statistics. OPTIONS
There are no options. DISPLAY
Mach kernel version: The version string compiled into the kernel executing on the host system. Processor Configuration: The maximum possible processors for which the kernel is configured, followed by the number of physical and logical processors avail- able. Note: on Intel architectures, physical processors are referred to as cores, and logical processors are referred to as hardware threads; there may be multiple logical processors per core and multiple cores per processor package. This command does not report the number of processor packages. Processor type: The host's processor type and subtype. Processor active: A list of active processors on the host system. Active processors are members of a processor set and are ready to dispatch threads. On a single processor system, the active processor, is processor 0. Primary memory available: The amount of physical memory that is configured for use on the host system. Default processor set: Displays the number of tasks currently assigned to the host processor set, the number of threads currently assigned to the host proces- sor set, and the number of processors included in the host processor set. Load average: Measures the average number of threads in the run queue. Mach factor: A variant of the load average which measures the processing resources available to a new thread. Mach factor is based on the number of CPUs divided by (1 + the number of runnablethreads) or the number of CPUs minus the number of runnable threads when the number of runnable threads is less than the number of CPUs. The closer the Mach factor value is to zero, the higher the load. On an idle system with a fixed number of active processors, the mach factor will be equal to the number of CPUs. SEE ALSO
sysctl(8) Mac OS X October 30, 2003 Mac OS X
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