Subject: Re: mfs woes
To: Jonathan Stone <>
From: Chuck Silvers <>
List: tech-kern
Date: 07/19/2004 19:02:38
On Mon, Jul 19, 2004 at 12:53:20PM -0700, Jonathan Stone wrote:
> In message <>,
> Chuck Silvers writes:
> [...]
> >btw, a brief look at mdconfig shows that it uses exactly the same cute hack
> >to provide backing memory for its devices, so it should behave identically
> >to mfs with respect to memory usage.  it would be fairly easy to change md
> >to have the kernel allocate swap-backed memory directly, which would save
> >the context switch currently required to access data in the user-process
> >backing-store, but that wouldn't help with the double-memory-usage issue.
> What's the overall impact of that for setups using mdsetimage to build
> root-in-md setups (e.g., for booting from flash), with no swap?

the mdsetimage variation of this uses a preallocated kmem area,
so there should be no significant difference between that and the existing
allocate-kmem-on-demand thing or the new variation I mentioned above.
the new variation would only be different if there's swap space available.