Re: 2.2.18Pre Lan Performance Rocks!

["Jeff V. Merkey" <jmerkey@timpanogas.org>]

Daniel Phillips wrote:
> 
> "Jeff V. Merkey" wrote:
> >
> > Andrea Arcangeli wrote:
> > >
> > > Speaking only for myself: on the technical side I don't think you can't be much
> > > faster than moving the performance critical services into the kernel and by
> > > skipping the copies (infact I also think that for fileserving skipping the
> > > copies and making sendfile to work and to work in zero copy will be enough).
> > > So I don't think losing robusteness this way can be explained in any technical
> > > way and no, it's not by showing me money that you'll convince me that's a good
> > > idea.
> >
> > This would help, but not as much as full ring 0.
> 
> My experience is that I can get pretty much the same performance in ring
> 3 as ring 0 as long as I don't reload segment registers or take CR3.  Is
> this right, or am I missing some fundamental kind of ring 3 overhead?
> 
> Even in ring 0, you can mostly protect processes from each other using
> segments: if you don't reload the segments you can restrict damage to
> your own segment.  It's not 100% safety but it is an enormous
> improvement over running in the same address space as the OS kernel.  I
> don't have any problem at all with the idea of running a lot of parallel
> tasks in the same address space: the safety of this comes down to the
> compiler you use to compile the processes.  If the compiler doesn't have
> ops that let processes damage each other then you won't get damage,
> assuming no bugs in your underlying implementation.
> 
> BTW, let me add my 'me too': go for it, there is obviously a pot of gold
> there, just don't let Sauron^H^H^H^H^H^H Bill get to it first.


Amen to that one.  BTW.  The package we mailed out to you from Brian
went yesterday.  Let me know when it arrives.  I sent it to the address
in Berlin you provided.     

:-)

Jeff

> 
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> Daniel
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