Rumor has it that on Sat, Jan 31, 2004 at 10:30:37AM +0100 Jens Axboe said: > On Fri, Jan 30 2004, Joe Thornber wrote: > > It would be great to get some benchmarks to back up these arguments. > > eg, performance of dm mpath with a simple round robin selector, > > compared to a scsi layer implementation. Lifting the elevator (or > > lowering dm) is a big piece of work that I wont even consider unless > > there is very good reason; the reason probably needs to be broader > > than just multipath too. Even if we did decide to do this, it won't > > happen in 2.6. > > I suspect the problem really isn't that huge in 2.6, since most > performance file systems are using mpage or building their own big > bio's. So in a sense, some of the merging already does happen above dm > (and the io scheduler). Out of curiosity, where does raw io fit into that in 2.6? Thanks, Phil -- Philip R. Auld, Ph.D. Egenera, Inc. Principal Software Engineer 165 Forest St. (508) 858-2628 Marlboro, MA 01752
