summaryrefslogtreecommitdiffstats
path: root/share
diff options
context:
space:
mode:
authorjhb <jhb@FreeBSD.org>2003-04-21 20:05:33 +0000
committerjhb <jhb@FreeBSD.org>2003-04-21 20:05:33 +0000
commitc7835c09297d8fa5ed56c34caf126cebf5d1d9e9 (patch)
tree8ad2ca9e04847910fdee9af5fd23de46a087038e /share
parent78e84f94edccb374f445e3c024efb775be1000f8 (diff)
downloadFreeBSD-src-c7835c09297d8fa5ed56c34caf126cebf5d1d9e9.zip
FreeBSD-src-c7835c09297d8fa5ed56c34caf126cebf5d1d9e9.tar.gz
- Don't highlight options APIC_IO at the top since it only applies to i386
and this manpage is somewhat machine independent. - Don't redundantly say that SMP support is present for all supported architectures. Instead, say that it is present for all Tier-1 architectures. - Note that an SMP kernel not booting on a UP machine is an i386-only exception. - Add a paragraph about hyperthreading support including some docco on the machdep.hlt_logical_cpus sysctl ps@ recently added. - Note that SMP support for alpha, ia64, and sparc64 debuted in 5.0.
Diffstat (limited to 'share')
-rw-r--r--share/man/man4/smp.418
1 files changed, 15 insertions, 3 deletions
diff --git a/share/man/man4/smp.4 b/share/man/man4/smp.4
index 4a08799..1913a1f 100644
--- a/share/man/man4/smp.4
+++ b/share/man/man4/smp.4
@@ -31,20 +31,20 @@
.Nd description of the FreeBSD Symmetric MultiProcessor kernel
.Sh SYNOPSIS
.Cd options SMP
-.Cd options APIC_IO
.Sh DESCRIPTION
The
.Nm
kernel implements symmetric multiprocessor support.
.Sh COMPATIBILITY
-Support for multi-processor systems is present for all supported
+Support for multi-processor systems is present for all Tier-1
architectures on
.Fx .
Currently, this includes alpha, i386, ia64, and sparc64.
Support is enabled using
.Cd options SMP .
-On some, but not all platforms, it is permissible to use the SMP
+On most platforms it is permissible to use the SMP
kernel configuration on non-SMP equipped motherboards.
+The only exception to this rule is the i386 platform.
.Pp
For i386 systems, the
.Nm
@@ -57,6 +57,15 @@ i386 also requires
The
.Xr mptable 1
command may be used to view the status of multi-processor support.
+.Pp
+.Fx
+supports hyperthreading on Intel CPU's on the i386 platform.
+By default, logical CPUs are not used to execute user processes due to
+performance penalties under common loads.
+To allow the logical CPUs to execute user processes,
+turn off the
+.Va machdep.hlt_logical_cpus
+sysctl by setting its value to zero.
.Sh SEE ALSO
.Xr mptable 1 ,
.Xr condvar 9 ,
@@ -81,5 +90,8 @@ The SMPng Project relied heavily on the support of BSDi, who provided
reference source code from the fine-grained SMP implementation found
in
.Bsx .
+.Pp
+.Fx 5.0
+also introduced support for SMP on the alpha, ia64, and sparc64 architectures.
.Sh AUTHORS
.An Steve Passe Aq fsmp@FreeBSD.org
OpenPOWER on IntegriCloud