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sync with the new api.

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yamt 2005-10-16 04:06:20 +00:00
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commit e060d87164
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78
share/man/man9/bufq.9
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@ -1,4 +1,4 @@
.\" $NetBSD: bufq.9,v 1.8 2005/10/10 15:28:42 xtraeme Exp $
.\" $NetBSD: bufq.9,v 1.9 2005/10/16 04:06:20 yamt Exp $
.\"
.\" Copyright (c) 2002 The NetBSD Foundation, Inc.
.\" All rights reserved.
@ -34,7 +34,7 @@
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd October 10, 2005
.Dd October 16, 2005
.Dt BUFQ 9
.Os
.Sh NAME
@ -49,8 +49,8 @@
.Nd device buffer queues
.Sh SYNOPSIS
.In sys/bufq.h
.Ft void
.Fn bufq_alloc "struct bufq_state *bufq" "int flags"
.Ft int
.Fn bufq_alloc "struct bufq_state **bufq" "const char *strategy" "int flags"
.Ft void
.Fn bufq_drain "struct bufq_state *bufq"
.Ft void
@ -68,20 +68,33 @@ subsystem is a set of operations for the management of device buffer queues.
.Pp
The primary data type for using the operations is the
.Em bufq_state
structure in
.Pa sys/bufq.h :
.Bd -literal
struct bufq_state {
void (*bq_put)(struct bufq_state *, struct buf *);
struct buf *(*bq_get)(struct bufq_state *, int);
void *bq_private;
int bq_flags; /* Flags from bufq_alloc() */
};
.Ed
structure, which is opaque for users.
.Sh FUNCTIONS
.Bl -tag -width compact
.It Fn bufq_alloc "bufq" "strategy" "flags"
Allocate and initialize a
.Em bufq_state
descriptor.
.Pp
Valid values for the
.Em flags
argument are:
The argument
.Fa strategy
specifies a buffer queue strategy to be used for this buffer queue.
Following special values can be used.
.Pp
.Bl -tag -offset indent -width BUFQ_DISK_DEFAULT_STRAT -compact
.It Dv BUFQ_STRAT_ANY
Let
.Fn bufq_alloc
select a strategy.
.It Dv BUFQ_DISK_DEFAULT_STRAT
Let
.Fn bufq_alloc
select a strategy, assuming it will be used for a normal disk device.
.El
.Pp
Valid bits for the
.Fa flags
are:
.Pp
.Bl -tag -offset indent -width BUFQ_SORT_RAWBLOCK -compact
.It Dv BUFQ_SORT_RAWBLOCK
@ -92,25 +105,18 @@ sort by
.Em b_cylinder
and then by
.Em b_rawblkno
.It Dv BUFQ_FCFS
queue strategy is first-come first-serve
.It Dv BUFQ_DISKSORT
queue strategy is min seek sort
.It Dv BUFQ_READ_PRIO
queue strategy is min seek sort for writes and first-come first-serve
for reads with read priority
.It Dv BUFQ_PRIOCSCAN
queue strategy is per-priority cyclical scan
.It Dv BUFQ_EXACT
Fail if a strategy specified by
.Fa strategy
is not available.
In that case,
.Fa bufq_alloc
returns
.Dv ENOENT .
If this flag is not specified,
.Fn bufq_alloc
will silently uses one of available strategies.
.El
.Sh FUNCTIONS
.Bl -tag -width compact
.It Fn bufq_alloc "bufq" "flags"
Initialize a
.Em bufq_state
descriptor.
The argument
.Fa flags
controls the strategy and sort order.
.It Fn bufq_drain "bufq"
Drain a
.Em bufq_state
@ -140,7 +146,7 @@ if the queue is empty.
.Sh CODE REFERENCES
The actual code implementing the device buffer queues can be found
in the file
.Pa sys/kern/subr_disk.c .
.Pa sys/kern/subr_bufq.c .
.Sh HISTORY
The
.Nm