Interesting analysis of linux kernel threading by IBM

[Ed Tomlinson]

Peter Rival wrote:
> 
> Horst von Brand wrote:
> 
> > "Davide Libenzi" <davidel en maticad.it> said:
> >
> > [...]
> >
> > > my patch has great performance ( 80% with 300 tasks ) with a lot of tasks
> > > and low overhead ( 1.5% with 2 tasks ).
> > > And my patch has 0.00 optimizations about CPU fetches and Co.
> > > IMVHO 1-1.5 % of overhead is a price the we can afford given the performace
> > > with many tasks.
> > > My patch equals the current implementation with 8 tasks.
> >
> > So it is a net loss. This machine here (a personal workstation) has
> > typically 1 to 3 running tasks.
> >
> > Hondreds of tasks is just not a typical (perhaps even realistic)
> > workload.
> 
> No offense, but it is this type of thinking that will keep Linux out of the
> datacenter.  What you must say it is not a typical (or realistic) workload _for
> me_.  Hundreds of tasks is trivial here - we have systems running with well over
> 100 users actively working that are two or more generations old (that's a much
> bigger thing for Alpha than for Intel).  On our newer systems we fully expect
> hundreds, if not thousands, of tasks.  The more commercially accepted Linux
> becomes, the more common large configurations are going to be, and we should be
> thinking about that now - not when we're being shot all over creation for not
> doing what everyone said we could (ala WinNT).

I have reciently moved from OS/2 to linux.  One the the things I miss most are applications
that do not block stupidly.  As linux threading improves, more and more, programs are going
to use threads and will become more and more responsive.  If java, if it catches on in linux, 
will also tend to use lots of threads.  Having a solution that costs a couple of percent on
lightly loaded boxes but saves when the system is pushed would seem to be a win in my books.

Ed Tomlinson <tomlins en cam.org>
http://www.cam.org/~tomlins/njpipes.html

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