Re: [PATCH 1/8] exofs: Kbuild, Headers and osd utils

[FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>]

On Mon, 16 Feb 2009 11:19:21 +0200
Boaz Harrosh <bharrosh@panasas.com> wrote:

> >> Also looking
> >> ahead I will have RAID 0, 1, 5, and 6 on objects of different devices. bio
> >> is the perfect collector for memory information in this situation.
> > 
> > You will add such features to exofs, handling multiple devices
> > internally?
> > 
> 
> Multiple objects on Multiple devices, Yes.

I thought that exofs is kinda example (reference) file system.

Nobody has seen your code. Let's discuss when we have the
code. Over-designing for what we've not seen is not a good idea.


> >> exofs is not the first and only file system who is using bios. Proof of
> >> the matter is that block exports a bio submit routine.
> > 
> > Seems that exofs just passes pages and the ULD sends a SCSI command
> > including these pages. I don't see how exofs needs to handle bio
> > directly.
> > 
> 
> How do you propose to collect these pages? and keep them without allocating
> an extra list? without pre-allocating a struct request? and without re-inventing
> the bio structure?

I don't think that allocating an extra list (or something) to keep
them hurts performance. We can talk about it when you have the real
performance results.