Re: Poor disk performance in NetBSD DomU, again

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

On Tue, May 13, 2014 at 3:50 PM, Yi Qiao <qiaoy%qiaoy.info@localhost> wrote:
> 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.


Sorry, I meant to paste the command line result, but Gmail sent the
message upon a mistake (cmd + enter ...)

nbsd# dd if=/dev/zero of=testfile bs=32k count=131072
131072+0 records in
131072+0 records out
4294967296 bytes transferred in 332.499 secs (12917233 bytes/sec)
nbsd# dd if=testfile of=/dev/null bs=32k
131072+0 records in
131072+0 records out
4294967296 bytes transferred in 33.847 secs (126893588 bytes/sec)


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