SMP(4) Kernel Interfaces Manual SMP(4) NAME SMP -- description of the FreeBSD Symmetric MultiProcessor kernel SYNOPSIS options SMP DESCRIPTION The SMP kernel implements symmetric multiprocessor support. COMPATIBILITY Support for multi-processor systems is present for all Tier-1 architectures on FreeBSD. Currently, this includes alpha, i386, ia64, and sparc64. Sup- port is enabled using options SMP. It is permissible to use the SMP kernel configuration on non-SMP equipped motherboards. I386 NOTES For i386 systems, the SMP kernel supports motherboards that follow the In- tel MP specification, version 1.4. In addition to options SMP, i386 also requires device apic. The mptable(1) command may be used to view the sta- tus of multi-processor support. FreeBSD supports hyperthreading on Intel CPU's on the i386 platform. Since using logical CPUs can cause performance penalties under certain loads, the logical CPUs can be disabled by setting the machdep.hlt_logical_cpus sysctl to one. SEE ALSO mptable(1), condvar(9), msleep(9), mtx_pool(9), mutex(9), sema(9), sx(9) HISTORY The SMP kernel's early history is not (properly) recorded. It was devel- oped in a separate CVS branch until April 26, 1997, at which point it was merged into 3.0-current. By this date 3.0-current had already been merged with Lite2 kernel code. FreeBSD 5.0 introduced support for a host of new synchronization primi- tives, and a move towards fine-grained kernel locking rather than reliance on a Giant kernel lock. The SMPng Project relied heavily on the support of BSDi, who provided reference source code from the fine-grained SMP imple- mentation found in BSD/OS. FreeBSD 5.0 also introduced support for SMP on the alpha, ia64, and sparc64 architectures. AUTHORS Steve Passe <fsmp@FreeBSD.org> FreeBSD 5.3 December 5, 2002 SMP(4)
NAME | SYNOPSIS | DESCRIPTION | COMPATIBILITY | I386 NOTES | SEE ALSO | HISTORY | AUTHORS
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