From owner-cvs-sys  Thu Apr 16 01:56:11 1998
Return-Path: <owner-cvs-sys>
Received: (from daemon@localhost)
          by hub.freebsd.org (8.8.8/8.8.8) id BAA20773
          for cvs-sys-outgoing; Thu, 16 Apr 1998 01:56:11 -0700 (PDT)
          (envelope-from owner-cvs-sys)
Received: from godzilla.zeta.org.au (godzilla.zeta.org.au [203.2.228.19])
          by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id BAA20572;
          Thu, 16 Apr 1998 01:55:25 -0700 (PDT)
          (envelope-from bde@godzilla.zeta.org.au)
Received: (from bde@localhost)
	by godzilla.zeta.org.au (8.8.7/8.8.7) id SAA04053;
	Thu, 16 Apr 1998 18:51:05 +1000
Date: Thu, 16 Apr 1998 18:51:05 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199804160851.SAA04053@godzilla.zeta.org.au>
To: cvs-all@FreeBSD.ORG, cvs-committers@FreeBSD.ORG, cvs-sys@FreeBSD.ORG,
        peter@FreeBSD.ORG
Subject: Re: cvs commit: src/sys/kern vfs_subr.c
Sender: owner-cvs-sys@FreeBSD.ORG
X-Loop: FreeBSD.org
Precedence: bulk

>  Modified files:
>    sys/kern             vfs_subr.c 
>  Log:
>  When the softdep conversion took place, the periodic vfs_msync() from
>  update got lost.  This is responsible for ensuring that dirty mmap() pages
>  get periodically written to disk.  Without it, long time mmap's might not
>  have their dirty pages written out at all of the system crashes or isn't
>  cleanly shut down.  This could be nasty if you've got a long-running
>  writing via mmap(), dirty pages used to get written to disk within 30
>  seconds or so.

sync_fsync() seems to be called too often for this (approx. every 3
seconds on an idle system).  vfs_msync() seems to do a lot every time
it is called.

We also lost control of the update interval.

We also lost waking the sync daemon in vm_pageout_scan().  There is
still a wakeup on vfs_update_wakeup, but nothing sleeps on it any
more.

A better quick fix for most of this is probably to resurrect the
update daemon and only call vfs_msync() from it.

Bruce