Am 29.06.2011 14:06, schrieb Anthony Liguori: > On 06/29/2011 06:59 AM, Kevin Wolf wrote: >> Hi, >> >> I think we have touched this topic before during some IRC discussions or >> somewhere deep in a mailing list thread, but I think it hasn't been >> discussed on the list. >> >> Our default cache mode of cache=writethrough is extremely conservative >> and provides absolute safety at the cost of performance, > > But for the most part, we track bare metal fairly well in terms of block > performance, no? > > Or are you really referring to qcow2 as a specific example? In the > past, we used a different default caching mode for qcow2. I think that > could be done again if there was a compelling reason.
No, people are also complaining about bad performance with raw. Which isn't really surprising when you do a flush after each single write request. O_SYNC is really much more than is needed in the average case. Kevin
