On 4/8/19 8:54 AM, 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. We can't just rename them since they've already been in a shipped kernel. The window for doing this passed long ago. -- Jens Axboe
