Date: Sun, 13 Apr 1997 14:38:47 -0400 (EDT) From: Mark Taylor <mtaylor@cybernet.com> To: hackers@freebsd.org, bugs@freebsd.org Subject: vnode as filesystem (crash!) Message-ID: <XFMail.970413160017.mtaylor@cybernet.com>
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I'm trying to use a vnode as a file system.
I have no problem "vnconfig"ing and "newfs"ing it (a 10 MB test
case, derived from "dd" and /dev/zero).
The problem comes when I start creating files on the mounted
vnode. I can get a few hundred files created (this is a random
number: sometimes a few hundred, but never more than two thousand),
and then it hangs the system (actually, sometimes it causes a reboot).
No panics, no kernel messages, just a hang/reboot. I haven't tried the
kernel debugger yet (I don't know how to use it [yet].). :)
OS is FreeBSD 2.2.1-RELEASE. I've tried it on five other machines,
all with the same results. (All machines have at least 100 MBytes
of swap space, if that matters. None of which is used during these
tests, though). The results are universal, and exactly the same.
I've come up with a "fix":
1) In the makefiles script, I cause a 'sync' every 100 files created,
and all is fine- all of the 7500 files get created.
2) Instead of the /bin/sync in the script, I change kern.update from
the default 30 to 5. All 7500 files get made, no problem.
So there seems to be a problem with the vm/fs cache? I'd hate to live
with a 5 second update time.
The sequence of events is:
dd if=/dev/zero of=/tmp/T0 bs=1024 count=10240
vnconfig -c -s labels /dev/vn0 /tmp/T0
disklabel -w -r vn0 tenmeg
newfs -i 1024 /dev/vn0a # need lots of inodes for makefiles created files
mount /dev/vn0a /mnt
/root/bin/makefiles # script to create 100 files per directory of 1k each
(system hangs/reboots in a few seconds, no messages)
The disklabel tenmeg (from /etc/distab):
tenmeg:ty=mfs:se#512:nt#1:rm#300:\
:ns#20480:nc#1:\
:pa#20480:oa#0:ba#4096:fa#512:ta=4.2BSD:\
:pc#20480:oc#0:bc#4096:fc#512:
The "makefiles" script: (it's a hack- no comments please!)
#!/bin/csh
set i=0
set files=100
mkdir $files; cd $files
while ( `/bin/test $files -gt 7500; echo -n $status` )
# echo -n "$files "
if ( `/bin/test $i -ne 100; echo -n $status` ) then
echo "$files"
#/bin/sync
cd ..
mkdir $files
cd $files
set i=0
endif
@ i++
dd if=/dev/zero of=$i bs=1024 count=1 >& /dev/null
@ files++
end
echo ""
Please include my email address in responses, as I am not
directly on the hackers list.
--------------------------------------------------------------------
Mark J. Taylor Network R&D Manager
Cybernet Systems mtaylor@cybernet.com
727 Airport Blvd. PHONE (313) 668-2567
Ann Arbor, MI 48108 FAX (313) 668-8780
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