Attachment 108689 Details for Bug 149574 – file.diff

[patch] file.diff

file.diff (text/plain), 6.18 KB, created by pluknet on 2010-08-12 14:40:04 UTC

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Creator: pluknet

Created: 2010-08-12 14:40:04 UTC

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obsolete

>Index: share/man/man9/mi_switch.9
>===================================================================
>--- share/man/man9/mi_switch.9	(revision 209664)
>+++ share/man/man9/mi_switch.9	(working copy)
>@@ -1,4 +1,4 @@
>-.\"	$NetBSD: ctxsw.9,v 1.2 1996/12/02 00:11:31 tls Exp $
>+.\"	$NetBSD: ctxsw.9,v 1.3 1997/10/08 22:00:23 jtc Exp $
> .\"
> .\" Copyright (c) 1996 The NetBSD Foundation, Inc.
> .\" All rights reserved.
>@@ -18,8 +18,8 @@
> .\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
> .\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
> .\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
>-.\" PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
>-.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
>+.\" PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
>+.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
> .\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
> .\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
> .\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
>@@ -29,7 +29,7 @@
> .\"
> .\" $FreeBSD$
> .\"
>-.Dd November 24, 1996
>+.Dd August 12, 2010
> .Dt MI_SWITCH 9
> .Os
> .Sh NAME
>@@ -41,21 +41,21 @@
> .In sys/param.h
> .In sys/proc.h
> .Ft void
>-.Fn mi_switch "void"
>+.Fn mi_switch "int flags" "struct thread *newtd"
> .Ft void
>-.Fn cpu_switch "void"
>+.Fn cpu_switch "struct thread *td" "struct thread *newtd" "struct mtx *td_lock"
> .Ft void
>-.Fn cpu_throw "void"
>+.Fn cpu_throw "struct thread *td" "struct thread *newtd"
> .Sh DESCRIPTION
> The
> .Fn mi_switch
>-function implements the machine independent prelude to a thread context
>+function implements the machine-independent prelude to a thread context
> switch.
> It is called from only a few distinguished places in the kernel
> code as a result of the principle of non-preemptable kernel mode execution.
>-The various major uses of
>-.Nm
>-can be enumerated as follows:
>+The various major uses of the
>+.Fn mi_switch
>+function can be enumerated as follows:
> .Bl -enum -offset indent
> .It
> From within a function such as
>@@ -71,13 +71,12 @@
> (e.g.\& a system call, device interrupt)
> when the kernel prepares a return to user-mode execution.
> This case is
>-typically handled by machine dependent trap-handling code after detection
>+typically handled by machine-dependent trap-handling code after detection
> of a change in the signal disposition of the current process, or when a
> higher priority thread might be available to run.
> The latter event is
>-communicated by the machine independent scheduling routines by calling
>-the machine defined
>-.Fn need_resched .
>+communicated by the machine-independent scheduling routines by setting
>+the needresched thread state.
> .It
> In the signal handling code
> (see
>@@ -94,7 +93,9 @@
> the process as a whole.
> .El
> .Pp
>+The
> .Fn mi_switch
>+function
> records the amount of time the current thread has been running in the
> process structures and checks this value against the CPU time limits
> allocated to the process
>@@ -108,51 +109,89 @@
> .Pp
> If the thread is still in the
> .Dv TDS_RUNNING
>-state,
>+state, the
> .Fn mi_switch
>+function
> will put it back onto the run queue, assuming that
> it will want to run again soon.
>-If it is in one of the other
>-states and KSE threading is enabled, the associated
>-.Em KSE
>-will be made available to any higher priority threads from the same
>-group, to allow them to be scheduled next.
> .Pp
>-After these administrative tasks are done,
>+If a
>+.Fa newtd
>+thread is
>+.Dv NULL ,
>+the
> .Fn mi_switch
>-hands over control to the machine dependent routine
>-.Fn cpu_switch ,
>-which will perform the actual thread context switch.
>+function will hand over control to the machine-dependent
>+.Fn cpu_switch
>+function to select a new thread from the system run queue.
>+If a new thread is specified, then the CPU will switch to that thread
>+directly rather than calling
>+.Xr choosethread 9
>+to pick a thread to choose to.
>+The
>+.Fa flags
>+argument specifies a conjunction of the types and flags for the
>+.Fn mi_switch
>+function.
>+The currently understood flags are:
> .Pp
>+.Bd -literal -offset indent -compact
>+SW_VOL		Voluntary switch,
>+SW_INVOL	Involuntary switch,
>+SW_PREEMPT	Involuntary switch is a preemption
>+.Ed
>+.Pp
>+Currently defined types are:
>+.Pp
>+.Bd -literal -offset indent -compact
>+SW_TYPE_MASK		First 8 bits are switch type,
>+SWT_NONE		Unspecified switch,
>+SWT_PREEMPT		Switching due to preemption,
>+SWT_OWEPREEMPT		Switching due to opepreempt,
>+SWT_TURNSTILE		Turnstile contention,
>+SWT_SLEEPQ		Sleepq wait,
>+SWT_SLEEPQTIMO		Sleepq timeout wait,
>+SWT_RELINQUISH		yield call,
>+SWT_NEEDRESCHED		NEEDRESCHED was set,
>+SWT_IDLE		Switching from the idle thread,
>+SWT_IWAIT		Waiting for interrupts,
>+SWT_SUSPEND		Thread suspended,
>+SWT_REMOTEPREEMPT	Remote processor preempted,
>+SWT_REMOTEWAKEIDLE	Remote processor preempted idle
>+.Ed
>+.Pp
>+The
> .Fn cpu_switch
>-first saves the context of the current thread.
>-Next, it calls
>-.Fn choosethread
>-to determine which thread to run next.
>-Finally, it reads in the saved context of the new thread and starts to
>-execute the new thread.
>+function first saves the context of the current thread
>+.Fa td .
>+Then it reads in the saved context of the new thread
>+.Fa newtd
>+and starts to execute the new thread with the switchout
>+.Fa td_lock
>+mutex held.
> .Pp
>+The
> .Fn cpu_throw
>-is similar to
>+function is similar to the
> .Fn cpu_switch
>-except that it does not save the context of the old thread.
>+function
>+except that the former does not save the context of the old
>+.Fa td
>+thread.
> This function is useful when the kernel does not have an old thread
> context to save, such as when CPUs other than the boot CPU perform their
> first task switch, or when the kernel does not care about the state of the
> old thread, such as in
>-.Fn thread_exit
>+.Xr thread_exit 9
> when the kernel terminates the current thread and switches into a new
>+.Fa newtd
> thread.
>-.Pp
>-To protect the
>-.Xr runqueue 9 ,
>-all of these functions must be called with the
>-.Va sched_lock
>-mutex held.
> .Sh SEE ALSO
>+.Xr choosethread 9 ,
> .Xr cv_wait 9 ,
> .Xr issignal 9 ,
> .Xr mutex 9 ,
> .Xr runqueue 9 ,
> .Xr tsleep 9 ,
>+.Xr thread_exit 9 ,
> .Xr wakeup 9

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