lkml.org 
[lkml]   [1999]   [Nov]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Linux Buffer Cache Does Not Support Mirroring

Linus,

I can get done what I need for ship of the full NWFS (with mirroring) if
I can get an async interface to the disks that isn't tied into the
buffer cache from a memory consumption viewpoint. At present, the
interface still requires that I call getblk() for any buffer heads I
want to pass to the drivers. I need a way not to have to do this, so I
could simply pass my own buffer_head elements into ll_rw_block or
make_request(). I've found that when I do, all the drivers
malfunction. I want very much to work within a "Linux" framework, but I
realize that what's there just aint gonna' work without a sledge hammer
approach. Can you help?

Please advise,

Jeff

Linus Torvalds wrote:
>
> In article <381DC5A0.CABB7735@timpanogas.com>,
> Jeff V. Merkey <jmerkey@timpanogas.com> wrote:
> >
> >What everyone is side-stepping is that the interface between the drivers
> >and the buffer cache is incestuous -- this prevents folks from building
> >async I/O based FS's on Linux. The solution is not a simple one -- the
> >drivers and buffer cache interface needs to be changed to elimnate these
> >dependencies so.
>
> Actually, not at all.
>
> The way to fix what you call "incestuous" is to just marry the two off
> for good. They aren't incestuous, they're just living in sin..
>
> The buffer cache is closely related to the drivers, and will become only
> _MORE_ closely related to the drivers. That's because the buffer cache
> is quite consciously being evolved into just a driver interface for IO:
> the "buffer cache" is transforming away from a "cache", and into a pure
> "block IO interface".
>
> So no, the buffer cache doesn't support the kind of mirroring you want,
> and almost certainly never will. But the page cache may eventually
> evolve into the direction you're looking for.
>
> Linus
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.rutgers.edu
> Please read the FAQ at http://www.tux.org/lkml/

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:54    [from the cache]
©2003-2011 Jasper Spaans. Advertise on this site