On Mon, Jun 01, 2020 at 01:36:54PM +0200, Linus Walleij wrote: > On Mon, Jun 1, 2020 at 9:50 AM Ming Lei <ming.lei@xxxxxxxxxx> wrote: > > On Thu, May 28, 2020 at 10:10:03AM +0200, Linus Walleij wrote: > > > The Kyber block scheduler is not suitable for single hardware > > > queue devices, so add a new flag for single hardware queue > > > devices and add that to the deadline and BFQ schedulers > > > so the Kyber scheduler will not be selected for single queue > > > devices. > > > > The above may not be true for some single hw queue high performance HBA( > > such as megasas), which can get better performance from none, so it is > > reasonable to get better performance from kyber, see 6ce3dd6eec11 ("blk-mq: > > issue directly if hw queue isn't busy in case of 'none'"), and the > > following link: > > > > https://lore.kernel.org/linux-block/20180710010331.27479-1-ming.lei@xxxxxxxxxx/ > > I see, but isn't the case rather that none is preferred and kyber gives > the same characteristics because it's not standing in the way > as much? Kyber has its own characteristic, such as fair read & write, better IO merge. And the decision on scheduler isn't only related with device, but also with workloads. > > It looks like if we should add a special flag for these devices with > very fast single queues so they can say "I prefer none", do you > agree? I am not sure if it is easy to add such flag, because it isn't only related with HBA, but also with the attached disks. Thanks, Ming ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/