Re: Linux v.s. Mac OS-X Performance

On 11/28/07, Magnus Hagander <magnus@hagander.net> wrote:

> On Wed, 2007-11-28 at 07:29 -0700, Scott Ribe wrote:
> > > Yes, very much so. Windows lacks the fork() concept, which is what makes
> > > PostgreSQL much slower there.
> >
> > So grossly slower process creation would kill postgres connection times. But
> > what about the cases where persistent connections are used? Is it the case
> > also that Windows has a performance bottleneck for interprocess
> > communication?
>
> There is at least one other bottleneck, probably more than one. Context
> switching between processes is a lot more expensive than on Unix (given
> that win32 is optimized towards context switching between threads). NTFS
> isn't optimized for having 100+ processes reading and writing to the
> same file. Probably others..

I'd be interested to know what this info is based on.  The only
fundamental difference between a process and a thread context switch
is VM mapping (extra TLB flush, possible pagetable mapping tweaks).
And why would NTFS care about anything other than handles?

I mean, I can understand NT having bottlenecks in various areas
compared to Unix, but this "threads are specially optimized" thing is
seeming a bit overblown.  Just how often do you see threads from a
single process get contiguous access to the CPU?