* Mark Wagner <mwagner@xxxxxxxxxx> [2008-10-13 14:06]:
> Ryan Harper wrote:
> Can you please post the details of the guest and host configurations.
> From seeing kvm write data that is greater than that of bare metal,
> I would think that your test dataset is too small and not
> exceeding that of the host cache size.
The size was chosen so it would fit in to demonstrate the crazy #'s seen
on cached writes without O_DSYNC.
> Our previous testing has shown that once you exceed the host cache
> and cause the cache to flush, performance will drop to a point lower
> than if you didn't use the cache in the first place.
> Can you repeat the tests using a data set that is 2X the size of your
> hosts memory and post the results for the community to see?
Yeah, I can generate those numbers as well. Seeing your note about tons
of ESA and storage, feel free to generate your own #'s and post them for
the community as well; the more the merrier.
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
(512) 838-9253 T/L: 678-9253