On Wednesday, January 15, 2020 at 7:16:48 AM UTC-8, Bobby wrote: > > > Hi all, > > I have a question regarding multi-queue in iSCSI. AFAIK, *scsi-mq* has > been functional in kernel since kernel 3.17. Because earlier, > the block layer was updated to multi-queue *blk-mq* from single-queue. So > the current kernel has full-fledged *multi-queues*. > > The question is: > > How an iSCSI initiator uses multi-queue? Does it mean having multiple > connections? I would like > to see where exactly that is achieved in the code, if someone can please > me give me a hint. Thanks in advance :) > > Regards >
open-iscsi does not use multi-queue specifically, though all of the block layer is now converted to using multi-queue. If I understand correctly, there is no more single-queue, but there is glue that allows existing single-queue drivers to continue on, mapping their use to multi-queue. (Someone please correct me if I'm wrong.) The only time multi-queue might be useful for open-iscsi to use would be for MCS -- multiple connections per session. But the implementation of multi-queue makes using it for MCS problematic. Because each queue is on a different CPU, open-iscsi would have to coordinate the multiple connections across multiple CPUs, making things like ensuring correct sequence numbers difficult. Hope that helps. I _believe_ there is still an effort to map open-iscsi MCS to multi-queue, but nobody has tried to actually do it yet that I know of. The goal, of course, is better throughput using MCS. -- You received this message because you are subscribed to the Google Groups "open-iscsi" group. To unsubscribe from this group and stop receiving emails from it, send an email to open-iscsi+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/open-iscsi/8f236c4a-a207-4a0e-8dff-ad14a74e57dc%40googlegroups.com.
