x64 speed

[David Cournapeau]

On Wed, Feb 4, 2009 at 2:36 AM, Robin Becker <robin at reportlab.com> wrote:
> Whilst doing some portability testing with reportlab I noticed a strange
> speedup for our unittest suite with python2.5
>
> host  win32 xp3 unittest time=42.2 seconds
> vmware RHEL x64 unittest time=30.9 seconds
>
> so it looks like the vmware emulated system is much faster. Is it the x64
> working faster at its design sizes or perhaps the compiler or could it be
> the vmware system caching all writes etc etc? For the red hat x64 build the
> only special configuration was to use ucs2
>
> I know that the VT bit stuff has made virtualization much better, but this
> seems a bit weird.

It can be many things of course depending on your configuration and
what you are doing in your unit tests, but I don't find it weird at
all. I often see faster results when IO is involed in my Ubuntu in
vmware fusion than on mac os X - again, can be that the vm is not
loaded (less python packages, faster import times), Linux better IO
handling (I don't know whether this is true or not, but I could at
least imagine that linux FS generally being faster than windows or mac
os X ones, this could influence IO)

It can also be compilers differences, 32 vs 64 bits as you say, etc...
If you want to be sure, you should try a window VM :)

David