Date: Sat, 8 Aug 1998 10:48:43 -0700 (PDT) From: Matthew Dillon <dillon@backplane.com> To: Terry Lambert <tlambert@primenet.com> Cc: wollman@khavrinen.lcs.mit.edu (Garrett Wollman), freebsd-fs@FreeBSD.ORG Subject: Re: Filesystem locking during lookups Message-ID: <199808081748.KAA19458@apollo.backplane.com>
next in thread | raw e-mail | index | archive | help
Well, I've seen cascade crashes where locks are held all the
way to root, but ultimately it comes down to a deadlock on some
deep file or directory. But, again, it's doubtful that namei has
anything to do with it. It's more likely to be a deadlock in the
filesystem vs VM code.
I changed Diablo's feeder code on my test machine to avoid
appending to the history file on each write (instead, it appends
a large block of zero's and then allocates history records
out of the block). nntp3.ba.best.com has been the most stable
it's been yet... up 9 days now.
However, I am still seeing significant VM/fs corruption where
the mmaping of files being actively appended to (in this case,
the spool files) can cause physical corruption of the file.
-Matt
:>
:> In 30 seconds, my machine made 1475 calls to namei, of which 209 were
:> root-relative. Even with these changes, my machine still deadlocked
:> last night (although it lasted longer than it did the night before),
:> so I would say that there is a fair amount of filesystem contention
:> going on.
:
:Are you running soft updates?
:
:I have a *very* hard time believing that the lock is being held
:all the way up to root, intentionally. There's simply no code
:to actually reverse traverse freeing the locks.
:
:Perhaps locked vnodes are being cached with the lock held in some
:way?
:
:Is your news spool mounted right off of root?
:
:
:I'm also very interested in your root vs. relative path count; can you
:say what the single largest culprit for this is? Is there a single
:largest culprit responsible for absolute path lookup?
:
:
: Terry Lambert
: terry@lambert.org
:---
:Any opinions in this posting are my own and not those of my present
:or previous employers.
:
Matthew Dillon Engineering, HiWay Technologies, Inc. & BEST Internet
Communications
<dillon@backplane.com> (Please include original email in any response)
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-fs" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199808081748.KAA19458>