Re: [Xen-devel] Does blkback bypass Dom0's memory buffer?

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On 04/02/14 22:15, xu cong wrote:
> Does blkback thread bypass Dom0's memory buffer? If I write in DomU
> without O_Direct, the data will be buffered in DomU's memory cache then
> be flushed to disk. Will them be buffered in Dom0's memory again? How
> about the netback? Thanks.

Blkback will not do any kind of buffering itself, the request is read
from the shared ring and passed to the underlying device using
submit_bio. If you want to make sure your data has hit the disk you
should issue a flush operation (see "feature-flush-cache" in blkif.h)

Roger.


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