Disk I/O as a bottleneck?

[Gilboa Davara]

On Sun, 2011-05-08 at 14:56 +0000, is123 at zahav.net.il wrote:
> On Sun, 08 May 2011 17:28:07 +0300
> Gilboa Davara <gilboad at gmail.com> wrote:
> 
> > On Sun, 2011-05-08 at 07:31 +0000, is123 at zahav.net.il wrote:
> > >
> > > at this point Linux (and BSD) still aren't doing SMP
> > > as well as other OS
> > 
> > Care to elaborate?
> 
> I think it's well-known Solaris exploits multicore better than Linux or
> BSD. 

I have very little experience in BSD OS', so I can't really comment on
that.
However, in my own experience, the SMP performance of Linux vs. Solaris
-greatly- depends on workload, with each having its own advantages and
disadvantages.


> I don't track Linux very much but I can see from conky on my boxes Linux
> just doesn't do that well. And race conditions are unfortunately an
> ongoing problem in many apps.

I don't think race condition means what you think it means...
You're most likely mixing race condition and resource / lock contention.

More-ever, you're mixing SMP kernel issues (Such as the
soon-to-be-officially-dead BKL [big kernel lock] and SMP scheduler
issues) and application design issues. (Read: Application that are not
design with big/huge-SMP in mind)

> 
> I work on a different platform where multithreading and multiprocessing
> were a very early part of the design and I have seen a big difference in
> performance and lack of race conditions in that environment because it was
> based on a native multithreading model whereas UNIX was based on process
> forking and threading came much later and you could argue was not exactly
> implemented seamlessly. It's not an apples and apples comparison but the
> difference in software issues on those systems is night and day. As far as I
> can see those problems still haven't been resolved at the design or
> implementation levels.

A specific example will go a long way to explain your POV.

- Gilboa