I have colinux running on a Fedora Core 1 image.  I have the rhdb 3 (or
PostgreSQL RedHat Edition 3) on it running.  Here are tests with fsync on
and off:
  FSYNC OFF               FSYNC ON              RUN
136.9    142.0  124.5    149.1  1
122.1    126.7  140.1    169.7  2
125.7    148.7  147.4    180.4  3
103.3    136.7  136.8    166.3  4
126.5    146.1  152.3    187.9  5
114.4    133.3  144.8    176.7  6
124.0    146.5  143.3    175.0  7
121.7    166.8  147.8    180.5  8
127.3    151.8  146.7    180.0  9
124.6    143.0  137.2    167.5  10
122.7    144.2  142.1    173.3  AVG

I hope those numbers' formatting come through all right.  

This computer is an AMD Athlon 900MHz with 448MB Ram running XP Pro SP1
This is using Colinux 0.60 (not the recently released 0.61) and 96MB of RAM
allocated to linux.

The computer was idle but it was running Putty, Excel and Task Manager
during the process.  (I prefer to use Putty to SSH into the virtual computer
than to run the fltk console)

It occurs to me that the fsync may be performed to the linux filesystem, but
this filesystem is merely a file on the windows drive.  Would Windows cache
this file?  It's 2GB in size, so if it did, it would only be able to cache
part of it.

I'd like to run a more difficult test personally.  It seems like this test
goes too fast to be very useful.

If someone would like me to try something more specific, e-mail me right
away and I'll do it.  I must leave my office at 4:15 EDT and will not return
until Friday, although I can do another test on my home computer Thursday.

Matthew Nuzum           | Makers of "Elite Content Management System"
www.followers.net               | View samples of Elite CMS in action
[EMAIL PROTECTED]       | http://www.followers.net/portfolio/

> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:pgsql-performance-
> [EMAIL PROTECTED] On Behalf Of Tom Lane
> Sent: Wednesday, June 02, 2004 11:25 AM
> To: Greg Stark
> Cc: Vitaly Belman; [EMAIL PROTECTED]; Bryan Encina; Matthew
> Nuzum
> Subject: Re: [PERFORM] PostgreSQL on VMWare vs Windows vs CoLinux
> Greg Stark <[EMAIL PROTECTED]> writes:
> > That said, I'm curious why the emulated servers performed better than
> the
> > Native Windows port. My first thought is that they probably aren't
> syncing
> > every write to disk so effectively they're defeating the fsyncs,
> allowing the
> > host OS to buffer disk writes.
> It would be fairly easy to check this by repeating the comparisons with
> fsync = off in postgresql.conf.  A performance number that doesn't
> change much would be a smoking gun ;-).
> The native port hasn't had any performance testing done on it yet, and
> I wouldn't be surprised to hear of a gotcha or two.  Perhaps with the
> recent schedule change there will be some time for performance tuning
> before we go beta.
>                       regards, tom lane
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