Re: Poor disk performance in NetBSD DomU, again

[Yi Qiao <qiaoy%qiaoy.info@localhost>]

On Tue, May 13, 2014 at 2:01 PM, Manuel Bouyer 
<bouyer%antioche.eu.org@localhost> wrote:
> On Tue, May 13, 2014 at 01:47:46PM -0400, Yi Qiao wrote:
>> On Tue, May 13, 2014 at 1:33 PM, Manuel Bouyer 
>> <bouyer%antioche.eu.org@localhost> wrote:
>> > On Tue, May 13, 2014 at 01:29:23PM -0400, Yi Qiao wrote:
>> >> Hi Manuel
>> >>
>> >>   Sorry about that. It's all PV guests. And I don't think partition
>> >> alignments is the dominating issue here since after each experiment, I
>> >
>> > it can, depending on how the virtual disk is partitionned in the guest.
>>
>> I see. For the NetBSD installs, I simply partitioned xvda into / with
>> 9728M and swap with 512M. For the FreeBSD install, I accepted the
>> default partition scheme, which I think is a very small boot partition
>> at the beginning, 9G ish in the middle for /, and 512M as swap. For
>> Ubuntu, I let the installer create it's own lvm.
>>
>> The only straightforward way I can think to test the theory right now
>> is to change the order of the root and swap partitions during a NetBSD
>> install. However since the swap is only 512M, I doubt it will make a
>> noticeable difference.
>
> what's important is the root's partition start. By default it can
> be 63 or 2048 sectors, and this can make a difference with recent
> disks.

Do you mean the root partition of Dom0 or DomU? I tried to test on a
newly installed NetBSD DomU with the 2048 offset, and no difference
was observed.



>
> --
> Manuel Bouyer <bouyer%antioche.eu.org@localhost>
>      NetBSD: 26 ans d'experience feront toujours la difference
> --