On 3/12/21 3:53 PM, Ted Rodriguez-Bell wrote: > Yesterday Suse issued an s390-tools patch for SLES 12SP5 that does this: > > * Changing the scheduler from "deadline" to the newly created > "mq-deadline" scheduler (bsc#1176574) > (It takes us to 2.1.0-18.26.1 in case anyone's counting.) > > So two questions. First, it looks to me like mq-deadline is already there: > $ rpm -q s390-tools > s390-tools-2.1.0-18.23.1.s390x > $ cat /sys/block/dasda/queue/scheduler > [none] mq-deadline kyber bfq
It's available, but what's currently in use is "none." That's the value that's in square braces. > so what does the patch do? Second, how does the choice affect performance on > DASD devices? Does one even have a choice or does the device driver allow > only mq-deadline? It sets the scheduler to use mq-deadline (multi-queue deadline). You could, if you choose, override that with one of the other choices, but I wouldn't do that without getting some indication from one of IBM's performance folks that you should. Our direction from that source was that with the introduction of mq-deadline, that it was a better _default_ than any of the others. Mark Post ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www2.marist.edu/htbin/wlvindex?LINUX-390
