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authorjhb <jhb@FreeBSD.org>2005-04-04 21:53:56 +0000
committerjhb <jhb@FreeBSD.org>2005-04-04 21:53:56 +0000
commit41cadaa11ed081720fe75d25094f73a53d9bf55c (patch)
treed48c8aa642d31e026486326f9d281f4d5eff0bdb /sys/pc98/include
parent7d745ab8664182cd756c16538844d587ed753eb9 (diff)
downloadFreeBSD-src-41cadaa11ed081720fe75d25094f73a53d9bf55c.zip
FreeBSD-src-41cadaa11ed081720fe75d25094f73a53d9bf55c.tar.gz
Divorce critical sections from spinlocks. Critical sections as denoted by
critical_enter() and critical_exit() are now solely a mechanism for deferring kernel preemptions. They no longer have any affect on interrupts. This means that standalone critical sections are now very cheap as they are simply unlocked integer increments and decrements for the common case. Spin mutexes now use a separate KPI implemented in MD code: spinlock_enter() and spinlock_exit(). This KPI is responsible for providing whatever MD guarantees are needed to ensure that a thread holding a spin lock won't be preempted by any other code that will try to lock the same lock. For now all archs continue to block interrupts in a "spinlock section" as they did formerly in all critical sections. Note that I've also taken this opportunity to push a few things into MD code rather than MI. For example, critical_fork_exit() no longer exists. Instead, MD code ensures that new threads have the correct state when they are created. Also, we no longer try to fixup the idlethreads for APs in MI code. Instead, each arch sets the initial curthread and adjusts the state of the idle thread it borrows in order to perform the initial context switch. This change is largely a big NOP, but the cleaner separation it provides will allow for more efficient alternative locking schemes in other parts of the kernel (bare critical sections rather than per-CPU spin mutexes for per-CPU data for example). Reviewed by: grehan, cognet, arch@, others Tested on: i386, alpha, sparc64, powerpc, arm, possibly more
Diffstat (limited to 'sys/pc98/include')
-rw-r--r--sys/pc98/include/critical.h6
1 files changed, 0 insertions, 6 deletions
diff --git a/sys/pc98/include/critical.h b/sys/pc98/include/critical.h
deleted file mode 100644
index a3e7098..0000000
--- a/sys/pc98/include/critical.h
+++ /dev/null
@@ -1,6 +0,0 @@
-/*-
- * This file is in the public domain.
- */
-/* $FreeBSD$ */
-
-#include <i386/critical.h>
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