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Date:      Thu, 16 Apr 1998 18:51:05 +1000
From:      Bruce Evans <bde@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
Message-ID:  <199804160851.SAA04053@godzilla.zeta.org.au>

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>  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

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