Bug 19912

Comment 1 Sheldon Hearn 2000-07-14 13:27:16 UTC

Responsible Changed
From-To: freebsd-doc->sheldonh

Even if no syncer manual page is forthcoming, this cruft needs 
to go.  I'll make sure cross-references go away as well.

This is the proposed syncer(4) manual page that has been submitted to
<freebsd-hackers@FreeBSD.org>.

Ciao,
Sheldon.

------- Forwarded Message

From: Sheldon Hearn <sheldonh@uunet.co.za>
To: hackers@FreeBSD.org
Subject: Re: Where is the syncer kernel process implemented? 
In-reply-to: Your message of "Fri, 14 Jul 2000 14:32:11 +0200."
             <66316.963577931@axl.ops.uunet.co.za> 
Date: Fri, 14 Jul 2000 15:29:35 +0200
Message-ID: <67168.963581375@axl.ops.uunet.co.za>
Sender: sheldonh@axl.ops.uunet.co.za



On Fri, 14 Jul 2000 14:32:11 +0200, Sheldon Hearn wrote:

> I need to replace the update(4) manual page with a syncer(4) manual
> page.  Can someone please point me at the code that implements this
> process?

Alfred Perlstein pointed me at the correct code.  I used the update(4)
manual page as a starting point and came up with this after a fairly
lazy glance at the code.

Does it look alright?

Ciao,
Sheldon.

.\" Copyright (c) 2000 Sheldon Hearn <sheldonh@FreeBSD.org>
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.\" $FreeBSD$
.\"
.Dd July 14, 2000
.Dt SYNCER 4
.Os
.Sh NAME
.Nm syncer
.Nd filesystem synchronizer kernel process
.Sh SYNOPSIS
.Nm syncer
.Sh DESCRIPTION
The
.Nm
kernel process helps protect the integrity of disk volumes
by flushing volatile cached filesystem data to disk.
This is done at thirty second
.Pq actually Dv SYNCER_MAXDELAY - 2
intervals by default.
.Pp
The kernel places all
.Xr vnode 9 Ns 's
in a number of queues equal to
.Dv SYNCER_MAXDELAY .
The
.Nm
process works through the queues
in a round-robin fashion,
usually processing one queue per second.
For each
.Xr vnode 9
on the queue,
the 
.Nm
process forces a write out to disk of its dirty buffers.
.Sh SEE ALSO
.Xr sync 2 ,
.Xr fsck 8 ,
.Xr sync 8
.Sh BUGS
It is possible on some systems that a
.Xr sync 2
occurring simultaneously with a crash may cause
file system damage.  See
.Xr fsck 8 .
.Sh HISTORY
The
.Nm
process is a descendant of the
update
command, which apeared in
.At v6 ,
and was usually started by
.Pa /etc/rc
when the system went multi-user.
A kernel initiated
update
process first appeared in
.Fx 2.0 .

------- End of Forwarded Message

Comment 3 Sheldon Hearn 2000-07-20 08:37:58 UTC

State Changed
From-To: open->closed

A variant of the page proposed in the audit trail has been committed 
to HEAD and merged onto the RELENG_4 branch.  The update(4) page 
has been removed and all stale cross-references have been updated 
for syncer(4).