On 30/11/16 09:13, Yaniv Kaul wrote: > Thanks, but it really makes no sense to me. The direct IO by the VMs is > going to a different storage than what the host is writing to, in most > cases. > The host would write to the local disk, the VMs - to a shared storage, > across NFS or block layer or so. Moreover, their IO is not buffered. > There is very little IO coming from the host itself, generally (I hope > so!). > > Partially unrelated - the trend today is actually to put NOOP on the VMs - > the deadline is quite meaningless, as the host scheduler will reschedule > anyway as it see fits. > Most likely it is also a deadline scheduler (but could be NOOP as well if > it's an all flash array, for example). Therefore there is no reason for > anything but simple NOOP on the VMs themselves. > > In short, I think it's an outdated decision that perhaps should be > revisited. Not urgent, though. > Y.
I know it's not the most cared about usecase but I'd like to add that this might affect local storage domains, which I happen to use a lot, and maybe others too. -- Mit freundlichen Grüßen / Regards Sven Kieske Systemadministrator Mittwald CM Service GmbH & Co. KG Königsberger Straße 6 32339 Espelkamp T: +495772 293100 F: +495772 293333 https://www.mittwald.de Geschäftsführer: Robert Meyer St.Nr.: 331/5721/1033, USt-IdNr.: DE814773217, HRA 6640, AG Bad Oeynhausen Komplementärin: Robert Meyer Verwaltungs GmbH, HRB 13260, AG Bad Oeynhausen
signature.asc
Description: OpenPGP digital signature
_______________________________________________ Devel mailing list [email protected] http://lists.ovirt.org/mailman/listinfo/devel
