Subject: Re: that VM/fs cache coherency problem
To: None <tech-kern@NetBSD.ORG>
From: der Mouse <mouse@Collatz.McRCIM.McGill.EDU>
List: tech-kern
Date: 08/02/1995 06:55:38
>>> tail -f on logfiles is coredumping.
>> Is this over NFS?
> Actually, yesterday I had tail consistently fail for me exactly like
> in "der mouse"'s case, on a UFS partition.

I have been unable to reproduce the problem with tail.  But I have
found a way to provoke it consistently (this works even on the sparc):

	# cd /usr/src
	# make >& zerrs &
	# tail -f zerrs
...wait for a couple of lines to show up after tail -f prints its
initial blip of output, then in another window...
	# vi zerrs

vi sees the file with an up-to-date size, but contents as of the time
tail -f started up.  The space between that point and EOF is filled
with NULs.

I've been digging through the vm code, and have a couple of ideas about
what might cure this.  Haven't yet tried any of 'em yet though.

					der Mouse