Subject: Re: hexdumping large sparce files
To: David Laight <>
From: Bill Studenmund <>
List: tech-kern
Date: 01/24/2003 15:35:48
On Fri, 24 Jan 2003, David Laight wrote:

> Is there anything in the kernel that could be used to speed up the
> dumping of very large, very sparce files?
> For instance I would like to be able to verify the non-zero parts of
> the following file:
> $ ls -ls z
> 192 -rwxr-xr-x  1 dsl  wheel  14797279232 Jan 24 22:31 z
> without actually transferring 14Gb of data from kernel to user.
> (and maybe without filling all of physical memory with 0 bytes).

No. Our (and I believe POSIX) file semantics don't permit it.

If we had a good DMAPI implementation, we probably could do something, but
we don't. :-(

Take care,