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SubjectRe: NWFS Source Code Posted at 207.109.151.240

Andi,

The Linux Buffer Cache does not present a logical block cache for
NetWare's flavor of mirroring support, although basically what's there
is implemented as a Logical Block Cache on top of the Linux Buffer
Cache. You will notice that NWFS can use either it's own LRU or the
linux buffer cache (there's an #if/#else/#endif for LINUX_BUFFER_CACHE
in block.c -- this will make NWFS sit on top of buffer.c). You would
want to crank down the MAX_BLOCK_BUFFERS count in nwfs.h to something
smaller than 2000.

The Async processes bascially provides an elevator for remirroring and
concurrent mirroring I/O so the file system doesn't get starved. It
sits on top of the linux disk interface. These abstractions are also
necessary for our clustered file system for Linux (M2FS). Look
carefully at the layering in nwvp.c, and it will be clear why we did
what we did.

This code base also runs on several other platforms, and some of what is
there is not applicable to Linux, but is to NT and DOS. The tools use
these interfaces and we have to have them as convinient abstractions
since they are not available on every platform (not all OS's are as
blessed as Linux).

What's here is a smaller version of the internal architecture of Native
NetWare. Some of the services and what they do is a little different.
I hope we are helping Linux?

Very Truly Yours,

Jeff



Andi Kleen wrote:
>
> "Jeff V. Merkey" <jmerkey@timpanogas.com> writes:
> >
> > 1. Full Asynch IO Manager (SMP)
>
> Could you expand a bit on your reasons to use an own buffer cache
> instead of the standard Linux one ? Also what does this async
> manager offer over the normal asynchronous block device interface ?
>
> Thanks,
>
> -Andi
>
> -
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