Re: [Xen-users] Re: Windows Disk performance

[Ruslan Sivak <russ@xxxxxxxxxx>]

Christian Tramnitz wrote:
> Ruslan Sivak schrieb:
> > I've been getting disappointing results on IO reads when using 
> > windows guests.  I'm getting usually around 70MB/s reads using 
> > hdtune.  When installing James' PV drivers, the speed drops to about 
> > 20MB/s.
> > The host system is getting around 350MB/s reads.  I'm wondering if 
> > there is such a significant slowdown, or if my tests are somehow 
> > flawed.  The 70MB/s persisted throughout my VM testing, whether I was 
> > using Xen, XenSource or VMWare Server.
> > So my questions are:
> >
> > a.  Is there a bottleneck somewhere which basically caps the windows 
> > disk performance?
> > b. Is my testing methodology flawed.  Is there a better windows tool 
> > that will measure performance?  What about Linux tool?  I'm currently 
> > using hdparm -t
> > Russ
> Hi Russ,
>
> first of all let's clarify:
> - Is this Mb as in "Megabits per second" or MB as in "Megabytes per 
> second"? You stated both in your original post in the 0.95 driver 
> thread, so I want to make sure...
I would think MegaBytes per second. 
> - Did you use the same measurement/tools in all 3 scenarios (dom0, 
> domU/stock, domU/gplpv)? If yes how exactly? (I'm not aware of hdtune 
> for linux, so you most probably ran something else to get dom0 
> performance)
dom0 i used htdune -t /dev/sda
domU/stock and domU/gplpv I used hdtune. 
> I think the answer to #2 will explain the big difference between dom0 
> and domU performance (taking into account a bit of a general overhead).
> When it comes to PV driver's performance this is an interesting topic. 
> I've seen posts giving the opposite (not exact numbers but direction) 
> result, so it would be interesting to find out what causes this.
James mentioned something about something not being aligned properly.  
This might fix it, as on my dom0, I went from about 150mb/s with hdparm 
to 350 mb/s after adjusting some parameters as per the 3ware site. 

Russ

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users