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mdoc(7) police: hard sentence breaks, whitespace at EOL, contractions.

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Ruslan Ermilov 2002-03-15 18:04:00 +00:00
parent ba8bcff1e8
commit d78dca323f
1 changed files with 18 additions and 10 deletions
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28
lib/libc/sys/mmap.2
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@ -140,14 +140,17 @@ Causes data dirtied via this VM map to be flushed to physical media
only when necessary (usually by the pager) rather then gratuitously.
Typically this prevents the update daemons from flushing pages dirtied
through such maps and thus allows efficient sharing of memory across
unassociated processes using a file-backed shared memory map. Without
unassociated processes using a file-backed shared memory map.
Without
this option any VM pages you dirty may be flushed to disk every so often
(every 30-60 seconds usually) which can create performance problems if you
do not need that to occur (such as when you are using shared file-backed
mmap regions for IPC purposes). Note that VM/filesystem coherency is
mmap regions for IPC purposes).
Note that VM/filesystem coherency is
maintained whether you use
.Dv MAP_NOSYNC
or not. This option is not portable
or not.
This option is not portable
across
.Ux
platforms (yet), though some may implement the same behavior
@ -185,7 +188,8 @@ while reading a large file sequentially, e.g. using
The
.Xr fsync 2
function will flush all dirty data and metadata associated with a file,
including dirty NOSYNC VM data, to physical media. The
including dirty NOSYNC VM data, to physical media.
The
.Xr sync 8
command and
.Xr sync 2
@ -194,7 +198,8 @@ The
.Xr msync 2
system call is obsolete since
.Bx
implements a coherent filesystem buffer cache. However, it may be
implements a coherent filesystem buffer cache.
However, it may be
used to associate dirty VM pages with filesystem buffers and thus cause
them to be flushed to physical media sooner rather then later.
.It Dv MAP_PRIVATE
@ -218,10 +223,12 @@ and
This option creates
a memory region that grows to at most
.Fa len
bytes in size, starting from the stack top and growing down. The
bytes in size, starting from the stack top and growing down.
The
stack top is the starting address returned by the call, plus
.Fa len
bytes. The bottom of the stack at maximum growth is the starting
bytes.
The bottom of the stack at maximum growth is the starting
address returned by the call.
.El
.Pp
@ -302,7 +309,7 @@ below.)
.Dv MAP_FIXED
was specified and the
.Fa addr
parameter wasn't available.
parameter was not available.
.Dv MAP_ANON
was specified and insufficient memory was available.
The system has reached the per-process mmap limit specified in the
@ -322,7 +329,8 @@ sysctl.
.Xr make.conf 5
.Sh BUGS
.Fa len
is limited to 2GB. Mmapping slightly more than 2GB doesn't work, but
is limited to 2GB.
Mmapping slightly more than 2GB does not work, but
it is possible to map a window of size (filesize % 2GB) for file sizes
of slightly less than 2G, 4GB, 6GB and 8GB.
.Pp
@ -338,7 +346,7 @@ uses 32bit page indexes and
this gives
.Fx
a maximum of 8TB filesizes.
It's actually bugs in
It is actually bugs in
the filesystem code that causes the limit to be further restricted to
1TB (loss of precision when doing blockno calculations).
.Pp