Re: [BUG-2.5.24-BK] DriverFS panics on boot!

[Jens Axboe <axboe@suse.de>]

On Thu, Jul 04 2002, Andre Hedrick wrote:
> On Fri, 5 Jul 2002, Jens Axboe wrote:
> 
> > On Thu, Jul 04 2002, Andre Hedrick wrote:
> > > 	1) 8K writes and 64K (or larger) reads.
> > 
> > I've heard this before, but noone seems to have tested it yet. You know,
> > this is a couple of lines of change in ll_rw_blk.c and blkdev.h to
> > support this. Any reason you haven't done that, benched, and submitted
> > something to that effect? I'll even walk you through the 2.5 changes
> > needed to do this:
> 
> 
> [root@localhost mnt2]# bonnie -s 256

[snip bonnie results]

These mean nothing to me -- what are they, the base line or the changed
kernel? Or none of the above?!

> Using the hardware to help us and by working with it it, once can
> basically boost the write and slash the cpu usage.

You need to add some context to that statement.

> > > 	2) ONE maybe TWO passes on elevator operations.
> > 
> > Explain.
> 
> On writes restrict which are small the ordering is almost instant.
> Specifically ONE maybe TWO passes will sort.
> 
> Reads may need more as we optimize best on big reads.

So you are saying that writes don't need to be reordered as much,
because the drive typically does that? I guess that will always be true
with write back caching, I doubt that holds for write through.

And I don't quite follow the number of passes you compare, passes of
what? Insert and merge are a single pass per request, tops.

-- 
Jens Axboe