mdoc(7)'fy, fix broken FreeBSD release number (3.0.1 -> 3.1)

This commit is contained in:
Alexey Zelkin 1999-10-30 14:15:49 +00:00
parent 466f8f3f33
commit a169de1e31
Notes: svn2git 2020-12-20 02:59:44 +00:00
svn path=/head/; revision=52662

View File

@ -36,7 +36,9 @@
.Os
.Sh NAME
.Nm BUF
.Nd Kernel Buffer I/O scheme used in FreeBSD VM system
.Nd Kernel Buffer I/O scheme used in
.Fx
VM system
.Sh DESCRIPTION
.Pp
The kernel implements a KVM abstraction of the buffer cache which allows it
@ -45,7 +47,8 @@ to map potentially disparate vm_page's into contiguous KVM for use by
block sizes from DEV_BSIZE (usually 512) to upwards of several pages or more.
It also supports a relatively primitive byte-granular valid range and dirty
range currently hardcoded for use by NFS. The code implementing the
VM Buffer abstraction is mostly concentrated in /usr/src/sys/kern/vfs_bio.c.
VM Buffer abstraction is mostly concentrated in
.Pa /usr/src/sys/kern/vfs_bio.c .
.Pp
One of the most important things to remember when dealing with buffer pointers
(struct buf) is that the underlying pages are mapped directly from the buffer
@ -93,7 +96,7 @@ to the VFS device, not when the physical I/O is actually initiated. This
can create confusion within filesystem devices that use delayed-writes because
you wind up with pages marked clean that are actually still dirty. If not
treated carefully, these pages could be thrown away! Indeed, a number of
serious bugs related to this hack were not fixed until the 2.2.8/3.0.0 release.
serious bugs related to this hack were not fixed until the 2.2.8/3.0 release.
The kernel uses an instantiated VM buffer (i.e. struct buf) to placemark pages
in this special state. The buffer is typically flagged B_DELWRI. When a
device no longer needs a buffer it typically flags it as B_RELBUF. Due to
@ -117,8 +120,9 @@ system.
.Sh HISTORY
The
.Nm
manual page was originally written by Matthew Dillon and first appeared
in
.Fx 3.0.1 ,
manual page was originally written by
.An Matthew Dillon
and first appeared in
.Fx 3.1 ,
December 1998.