On Sun, Oct 20, 2013 at 08:58:58PM -0700, Sage Weil wrote: > It looks like without LVM we're getting 128KB requests (which IIRC is > typical), but with LVM it's only 4KB. Unfortunately my memory is a bit > fuzzy here, but I seem to recall a property on the request_queue or device > that affected this. RBD is currently doing
Unfortunately most device mapper modules still split all I/O into 4k chunks before handling them. They rely on the elevator to merge them back together down the line, which isn't overly efficient but should at least provide larger segments for the common cases. -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
