My best guess here is this: There is one work queue (IO QUEUE) per controller. Which in turn means that dm-crypt is fed by two queues and as such decides to have one kworker instance per queue. I might be completely wrong though. (Actually there's still mdraid, which seems to have accordingly 1/2 queues). Regards -Sven On Wed, February 26, 2014 16:12, "C. Dominik Bódi" wrote: > Am 26.02.2014 00:58, schrieb shmick@xxxxxxxxxx: >> *only* 150 ? >> there's lots of numbers here but maybe we should work backwards and KIS >> ask yourself what do you want to achieve ? >> when you know the results you want and/or need (2 different things) you >> can work backwards & figure out out how to get there >> do you *need* to have a certain read/write speed for your application or >> desired conclusion in mind ? > Well, yes, I'd like to have as much throughput as possible. The cpu is a > quad core with HT, so could dm-crypt not utilize 4 threads when there > are 4 disks in the raid5 array. > > An the thing is: > > 4 disks on controller A => dm-crypt 150MB/s > 2 disk on controller A, 2 disks on controller B => dm-crypt 300MB/s > > I don't understand that behaviour. Why does it make a difference for > dm-crypt if the disks sit on different controllers or not? Why should I > waste speed when dm-crypt could easily utilize 4 worker threads and max > out the raid5 performance? Why doesn't it do so automatically. Is there > any means to make dm-crypt use 4 threads even if all 4 drives sit on a > single controller? > _______________________________________________ dm-crypt mailing list dm-crypt@xxxxxxxx http://www.saout.de/mailman/listinfo/dm-crypt
