> Il giorno 8 apr 2019, alle ore 17:05, Jens Axboe <axboe@xxxxxxxxx> ha scritto: > > On 4/8/19 9:04 AM, Johannes Thumshirn wrote: >> [+Cc Michal ] >> On Mon, Apr 08, 2019 at 04:54:39PM +0200, Paolo Valente wrote: >>> >>> >>>> Il giorno 8 apr 2019, alle ore 16:49, Johannes Thumshirn <jthumshirn@xxxxxxx> ha scritto: >>>> >>>> On Mon, Apr 08, 2019 at 04:39:35PM +0200, Paolo Valente wrote: >>>>> From: Angelo Ruocco <angeloruocco90@xxxxxxxxx> >>>>> >>>>> When bfq was merged into mainline, there were two I/O schedulers that >>>>> implemented the proportional-share policy: bfq for blk-mq and cfq for >>>>> legacy blk. bfq's interface files in the blkio/io controller have the >>>>> same names as cfq. But the cgroups interface doesn't allow two >>>>> entities to use the same name for their files, so for bfq we had to >>>>> prepend the "bfq" prefix to each of its files. However no legacy code >>>>> uses these modified file names. This naming also causes confusion, as, >>>>> e.g., in [1]. >>>>> >>>>> Now cfq has gone with legacy blk, so there is no need any longer for >>>>> these prefixes in (the never used) bfq names. In view of this fact, this >>>>> commit removes these prefixes, thereby enabling legacy code to truly >>>>> use the proportional share policy in blk-mq. >>>>> >>>>> [1] https://github.com/systemd/systemd/issues/7057 >>>> >>>> Hmm, but isn't this a user-space facing interface and thus some sort of ABI? >>>> Do you know what's using it and what breaks due to this conversion? >>>> >>> >>> Yep, but AFAIK, the problem is exactly the opposite: nobody uses these >>> names for the proportional-share policy, or wants to use these names. I'm >>> CCing Lennart too, in case he has some improbable news on this. >>> >>> So the idea is to align names to what people expect, possibly before >>> more confusion arises. >> >> OK, crazy idea, not sure if Jens and Tejun will beat me for this, but >> symlinks? >> >> This way we can a) keep the old files and b) have them point to the new (a.k.a >> cfq style) files. > > I did consider that, and that would be doable. But honestly, I'm having a > hard time seeing what issue we are attempting to fix by doing this. > The problem is ~100% of people and software believing to set weights and not doing it. Paolo > -- > Jens Axboe
