> Il giorno 8 apr 2019, alle ore 17:11, Jens Axboe <axboe@xxxxxxxxx> ha scritto: > > On 4/8/19 9:06 AM, Paolo Valente wrote: >> >> >>> 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. > > I'm sorry, but I don't know what that means? > It means that people and code set weights, not bfq.weights. Thanks, Paolo > -- > Jens Axboe
