On 02/22/2017 11:42 AM, Linus Torvalds wrote: > On Wed, Feb 22, 2017 at 10:26 AM, Linus Torvalds > <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: >> >> And dammit, IF YOU DON'T EVEN KNOW, WHY THE HELL ARE YOU ASKING THE POOR USER? > > Basically, I'm pushing back on config options that I can't personally > even sanely answer. I got that much, and I don't disagree on that part. > If it's a config option about "do I have a particular piece of > hardware", it makes sense. But these new ones were just complete > garbage. > > The whole "default IO scheduler" thing is a disease. We should stop > making up these shit schedulers and then say "we don't know which one > works best for you". > > All it does is encourage developers to make shortcuts and create crap > that isn't generically useful, and then blame the user and say "well, > you should have picked a different scheduler" when they say "this does > not work well for me". > > We have had too many of those kinds of broken choices. And when the > new Kconfig options get so confusing and so esoteric that I go "Hmm, I > have no idea if my hardware does a single queue or not", I put my foot > down. > > When the IO scheduler questions were about a generic IO scheduler for > everything, I can kind of understand them. I think it was still a > mistake (for the reasons outline above), but at least it was a > comprehensible question to ask. > > But when it gets to "what should I do about a single-queue version of > a MQ scheduler", the question is no longer even remotely sensible. The > question should simply NOT EXIST. There is no possible valid reason to > ask that kind of crap. OK, so here's what I'll do: 1) We'll kill the default scheduler choices. sq blk-mq will default to mq-deadline, mq blk-mq will default to "none" (at least for now, until the new scheduler is done). 2) The individual schedulers will be y/m/n selectable, just like any other driver. I hope that works for everyone. -- Jens Axboe
