Re: File System Performance

[Linus Torvalds]

In article <[e-mail]>,
Andrew Morton  <[e-mail]> wrote:
>
>It's tar.  It cheats.  It somehow detects that the
>output is /dev/null, and so it doesn't read the input files.

Probably the kernel.

If you do a mmap()+write(), the write() to /dev/null won't even read the
mmap contents, which in turn will cause the pages to never be brought
in.

Anything which uses mmap+write will show this.

		Linus