Re: Device API: Implementation

Ingo Weinhold <bonefish-CFLBMwTPW48UNGrzBIF7/[email protected]> wrote:
> > > slow considering that the registrar has an always up to date 
> > > device
> > > list.
> > Well, syscalls should be faster than message passing, so that up-to
> > -
> > date list is probably not that beneficial (at least I think so).
> If you don't keep an up-to-date list somewhere, you'll have to run 
> the
> disk=5Fscanner functions everytime you want that information. And these 
> are
> magnitudes slower than a quick message exchange with the registrar.

That's absolutely correct.

> If the kernel keeps an up-to-date list anyway, the syscalls to fetch 
> the
> data are, of course, faster than the communication with the 
> registrar.

I think that's what I meant, otherwise, I was wrong ;-)

> To state my point of view cleary: I'm not entirely sure, that dealing 
> with
> the disk device stuff in the registrar is the best solution. Maybe 
> the
> kernel would be the better place. The kernel has some advantages, 
> like
> better performance, and later it may be necessary to copy/move much, 
> if
> not all, of the functionality there to be able to implement the nice 
> R2+
> features.
> 
> But there are also problems. To maintain an up-to-date list of disk
> devices, I want to use node and mount event monitoring, and that is
> currently not available. If we will provide it, things look 
> different.
> Furthermore there is the general question to be asked: Is it 
> necessary to
> implement that functionality in the kernel=3F Since I currently don't 
> think
> it is, I would tend to leave it in userland, unless there are 
> unbeatable
> benefits.

I'd say, let us do it in the registrar now (but still have the 
possibility of node monitoring in the kernel as well), if we will ever 
have a reason to move it into the kernel, that would be no problem, 
anyway.

> > > Very nice. I'm waiting with bated breath. ;-)
> > Don't do that too long :-))
> > I think I will first complete the stdio almost rewrite before 
> > following
> > the next topic :)
> Fair enough.

Well, I've spent too much time on that thing already :-/

Adios...
   Axel.