Re: [ANNOUNCE] iSCSI enterprise target software

[Ming Zhang <mingz@ele.uri.edu>]

On Wed, 2005-03-02 at 13:20, Bryan Henderson wrote:
> >u are talking about application aware caching/prefetching stuff. but i
> >prefer to modifying kernel page cache a little bit while make use of
> >most of the code there.
> 
> That's a powerful argument for using the page cache, and further, for 
> using it from within the kernel.  I once started a project to port a 
> particular filesystem driver from the kernel to user space.  It was to be 
> used in a Linux system whose sole purpose was to export one filesystem via 
> NFS.  I was looking for engineering ease.  Everything about porting the 
> driver to user space was almost trivial except for duplicating the page 
> cache, and that was enough work to call into question the whole strategy 
> (I never went far enough to actually make a decision).
> 
i tried several time before on implementing own cache structures in user
space/ kernel space. every time i think i can do it better than before.
but frankly, there are always corner cases that make it performs poor.


> But I'm sure there are cases where the tradeoff works.
yes. i am sure about this as well.

> 
> --
> Bryan Henderson                               San Jose California
> IBM Almaden Research Center                   Filesystems