On 9/12/18 2:58 AM, Takashi Iwai wrote: > 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 for verifying (and reporting), I'll get this in for 4.19-rc4. -- Jens Axboe
