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From: Blaisorblade <blaisorblade@yahoo.it>
To: user-mode-linux-devel@lists.sourceforge.net
Cc: Rob Landley <rob@landley.net>, Gerd Knorr <kraxel@bytesex.org>
Subject: Re: [uml-devel] SIGSEGV and SA_NODEFER
Date: Tue, 25 Jan 2005 20:34:25 +0100	[thread overview]
Message-ID: <200501252034.25668.blaisorblade@yahoo.it> (raw)
In-Reply-To: <200501251230.04080.rob@landley.net>

On Tuesday 25 January 2005 18:30, Rob Landley wrote:
> On Tuesday 25 January 2005 06:40 am, Blaisorblade wrote:
> > > Host is swapping, client configured without even support for swap.  (If
> > > I can get the darn client vmlinux down to 1 megabyte, I'd be thrilled.
> > > Didn't somebody once make the entire block layer configurable out once?
> > > With hostfs, I don't need it...)
> >
> > Do you trust hostfs so much? You don't need user IDs on your FS, I guess.
>
> Once I get /dev on ramfs managed by udev?  Not really, no.  I need the
> permissions to be right, but just about everything else should belong to
> root.  (Yeah, there are a couple fun tricks where files change their
> ownership to some variant of "nobody" to do chroot jails and stuff, but
> they do that at runtime...)
I don't expect chown to work at all - i.e. it's not "it forgets it at reboot", 
it's "it forgets it immediately"... If you see it working, maybe you are 
seeing the more precise behaviour "it forgets it As Soon as the file is 
closed".
> I've probably missed one or two instances, but I expect I can work around
> 'em...
>
> > I'm not at all happy with this, but I don't want someone using hostfs
> > over its possibilities. NFS is much better, anyway.
>
> NFS gives me hives
?? What's hives?
> (a stateless fileserver: okay, spot the contradiction in 
> terms here), although I must admit I haven't tried the new TCP/IP based
> version (V4?) yet because it wasn't finished last time I tried.
>
> > And somebody says it's also
> > faster (and since hostfs does limited caching, it makes sense - hostfs
> > must avoid having any inode cache, since it closes the host fd only when
> > the inode is evicted from the cache; I don't think it's possible to cache
> > data without an inode to link to, so it's clear it's slow).
>
> Since the host is cacheing the data for us, not having a redundant cache
> sounds like a good idea to me.  Admittedly, it's more syscalls, but less
> memory consumption...

The problem is that its slower than NFS!
-- 
Paolo Giarrusso, aka Blaisorblade
Linux registered user n. 292729
http://www.user-mode-linux.org/~blaisorblade


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  reply	other threads:[~2005-01-25 19:35 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-01-18 21:28 [uml-devel] SIGSEGV and SA_NODEFER Jeff Dike
2005-01-20  0:07 ` Blaisorblade
2005-01-20  3:52   ` Rob Landley
2005-01-21 12:35     ` Blaisorblade
2005-01-21 18:18       ` Rob Landley
2005-01-21 19:58         ` Blaisorblade
2005-01-22 16:34           ` Rob Landley
2005-01-24 19:45             ` Blaisorblade
2005-01-25  1:38               ` Rob Landley
     [not found]               ` <20050125084506.GA562@bytesex>
2005-01-25 10:16                 ` Blaisorblade
2005-01-25 10:16                   ` Rob Landley
2005-01-25 11:40                     ` Blaisorblade
2005-01-25 17:30                       ` Rob Landley
2005-01-25 19:34                         ` Blaisorblade [this message]
2005-01-25 19:30                           ` Rob Landley
2005-01-25 20:50                             ` Blaisorblade
2005-01-25 22:43                               ` Rob Landley
2005-01-21 13:09   ` Blaisorblade
2005-01-21 16:56     ` Jeff Dike

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