[reiserfs-list] Re: [OpenAFS-devel] more on the 2.2.18pre17 SMPcpu hog/etc.

[Jeffrey Hutzelman]

On 3 Dec 2000, Derek Atkins wrote:

> Hans Reiser <reiser@namesys.com> writes:
> 
> > The AFS code needs to store the key (at least 64 bits of it), not
> > the inode number, or performance is doomed when interacting with
> > reiserfs.
> 
> By the time that the AFS kernel code gets far enough to even obtain
> the "key", it's already opened the file.  Unless there is a portable
> way to obtain the key from user-space (considering that we cannot
> presume that we're using Reiserfs).
> 
> Basically, what happens is that at start-time the user-space code
> finds the inode number as I mentioned in the previous mail.  Then it
> passes that to the kernel, and the kernel immediately opens the file
> and pretty much keeps the file opened.  So, as long as the file inode
> is cached between the time the user-space code stat's the file and the
> kernel opens it, we're fine.

Not true.  Cache files are opened as needed; they are not kept open
permanently.  Only the CacheItems file and maybe the VolumeItems file
get that treatment.

-- Jeffrey T. Hutzelman (N3NHS) <jhutz+@cmu.edu>
   Sr. Research Systems Programmer
   School of Computer Science - Research Computing Facility
   Carnegie Mellon University - Pittsburgh, PA