Re: File System Performance

Linus Torvalds
2001-11-12T21:53:03Z

In article <3BF04289.8FC8B7B7@zip.com.au>,
Andrew Morton <akpm@zip.com.au> 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