Re: [Xen-users] XEN - Broadcom issue: survey

[Pezza <mario.beccia@xxxxxxxxxx>]

Hey Pasi,

it's Xen 3.1 compiled from stable source (downloaded last thursday).
It's running on a HP Proliant DL380 G5 with 6gb ram. Host OS is CentOS 5
(kernel 2.6.18 built inside Xen 3.1), guest is Win2K3 service pack 2.

The funny thing is that if I take the same disk image and the same conf file
and I run them on a XenExpress machine, everything runs fine and I see no
packet drop. Note that I said the same conf and image, thus I'm *not* using
PV, just the plain XenExpress server and a manual "xm create" command;
my XenExpress, thus, is running 3.0.4, not 3.1 and is on a different hw (you
can check earlier messages to this list for the details).

So, what I guess from this is that it's either an hw problem (network card
drivers?) or a difference in the kernel/dom0 configuration...

                                                                                
 
M.
                                                                          
M.


Pasi KÃrkkÃinen wrote:
> 
> On Wed, Nov 14, 2007 at 01:27:58PM -0800, Pezza wrote:
>> 
>> Pasi,
>> 
>> yes, definitely.
>> 
>> But, as I said, I'm not interested in performance here, just stability.
>> VMWare is slow without pv, but is stable (I can download gigs of data
>> from
>> machines on the same network with no problems; I can't do the same with a
>> Xen vm at the moment), while Xen, as of your words, is unstable without
>> PV.
>> 
>> Right?
>> 
> 
> Hmm.. it shouldn't be _unstable_ without PV drivers..
> 
> which version of Xen? Whist dom0 distribution and kernel? 
> 
> Which guest OS?
> 
> -- Pasi
> 
>>                                                                           
>> M.
>> 
>> 
>> Pasi KÃrkkÃinen wrote:
>> > 
>> > On Wed, Nov 14, 2007 at 10:29:09PM +0200, Pasi KÃrkkÃinen wrote:
>> >> On Wed, Nov 14, 2007 at 11:27:44AM -0800, Pezza wrote:
>> >> > 
>> >> > Pasi,
>> >> > 
>> >> > thanks for your reply.
>> >> > 
>> >> > I understood from this and other mailing lists that using an HVM
>> >> machine
>> >> > with no PV drivers would result in a poor performance, but it would
>> >> work
>> >> > anyway.
>> >> > My problem is that, due to this packet loss, HVM machines are not
>> >> usable,
>> >> > because they get some "strange" errors from time to time (session
>> >> breaks,
>> >> > corrupt files, etc...).
>> >> > So you're saying that lack of PV drivers is the cause and thus that
>> HVM
>> >> > machines are not stable if we don't use PV drivers?
>> >> > 
>> >> 
>> >> Basicly, yes.
>> >> 
>> >> HVM domU hardware emulation (NIC, disk controller, etc) is done by
>> QEMU
>> >> in
>> >> Xen.
>> >> 
>> >> QEMU people can possibly tell you more about expected performance and
>> >> problems.
>> >> 
>> >> And I bet you can find many comparisons with some googling..
>> performance
>> >> with and without PV drivers in HVM domU.
>> >> 
>> > 
>> > Btw same happens with VMware.. if you don't install "vmware tools"
>> > (=optimized drivers) you're limited to 10 Mbit/sec networking etc..
>> > 
>> > -- Pasi
>> > 
> 
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> 
> 

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