On Tue, 11 Sep 2018 18:54:19 +0200, Jens Axboe wrote: > > On 9/11/18 10:51 AM, Jeff Moyer wrote: > > Jens Axboe <axboe@xxxxxxxxx> writes: > > > >> On 9/11/18 10:48 AM, Jeff Moyer wrote: > >>> Jens Axboe <axboe@xxxxxxxxx> writes: > >>> > >>>> On 9/11/18 10:03 AM, Takashi Iwai wrote: > >>>>> Hi, > >>>>> > >>>>> I noticed that bfq doesn't appear in the I/O scheduler list on > >>>>> 4.19-rc3. It seems that blkcg_policy_register() at the beginning of > >>>>> bfq_init() returns -ENOSPC, hence the probe aborts silently. > >>>>> > >>>>> Is this already addressed? > >>>> > >>>> Haven't heard about this one before. What kernel did you last use that > >>>> worked? > >>> > >>> I'm guessing you just need to update the maximum number of policies: > >>> > >>> /* > >>> * Maximum number of blkcg policies allowed to be registered concurrently. > >>> * Defined here to simplify include dependency. > >>> */ > >>> #define BLKCG_MAX_POLS 3 > >> > >> That is my guess too, hence the suggestion to try and disable the > >> iolatency policy. Just tried here without, and it works, rebooting > >> with to verify that we're running out of policy slots. > > > > Functions calling this function: blkcg_policy_register > > > > File Function Line > > 0 block/bfq-iosched.c bfq_init 5675 ret = > > blkcg_policy_register(&blkcg_pol > > icy_bfq); > > 1 block/blk-iolatency.c iolatency_init 946 return > > blkcg_policy_register(&blkcg_pol > > icy_iolatency); > > 2 block/blk-throttle.c throtl_init 2511 return > > blkcg_policy_register(&blkcg_pol > > icy_throtl); > > 3 block/cfq-iosched.c cfq_init 4869 ret = > > blkcg_policy_register(&blkcg_pol > > icy_cfq); > > > > And then there were 4... > > Exactly. I'd bump it to 5 to leave room for one more, if we have to grow it > again, probably worth it to make it dynamic. So for, not really needed. Takashi, > can verify that the below fixes it up for you? Yes, it works. Tested-by: Takashi Iwai <tiwai@xxxxxxx> Thanks! Takashi
