Subject: Re: lfs panic on NetBSD-4.0_BETA2
To: None <>
From: Thor Lancelot Simon <>
List: tech-kern
Date: 12/19/2006 13:03:49
On Tue, Dec 19, 2006 at 06:22:09PM +0100, Joerg Sonnenberger wrote:
> On Tue, Dec 19, 2006 at 11:58:10AM -0500, Blair Sadewitz wrote:
> > Oh?  Simply by using it, or is there a specific operation?
> Simply by using it. It should be noted that it is heavily using mmap and
> msyncing ever chunk once it is done, so with enough bandwidth it can
> easily pressure LFS a lot.

I will note once again that this is severely buggy application behavior,
and that LFS will never -- and can never -- comfortably accomodate an
application which insists on abusing msync in this way: every single
call to msync will cause a partial-segment write.

And, of course, there is _no reason_ for a BitTorrent client to do anything
like this: if it ever happens to be the case that a chunk is not fully
written to disk, the standard startup check will reveal that that chunk
has an incorrect checksum, and it will simply be re-fetched.

LFS should not crash the system, but the application should also simply
not do this, or should not be used on LFS.

Thor Lancelot Simon	                           
  "The liberties...lose much of their value whenever those who have greater
   private means are permitted to use their advantages to control the course
   of public debate."					-John Rawls