Re: [PATCH] blk-throttle: fix repeat limit on bio with BIO_BPS_THROTTLED

[Yu Kuai]

Hi!

在 2024/04/22 11:33, 周泰宇 写道:
> What I want to do here was to set an easy to reach value to BPS_LIMIT (10M/s in this example) and an unable to reach value to IOPS_LIMIT (100000 in this example).
>
>
> Under this setting, the iostat shows that the bps is far less than 10M/s and sometimes is far larger than 10M/s.

Yes, I know this behaviour, and this is because blk-throttle works
before IO split, and io stats is accounting bps for rq-based disk after
IO split, if you using Q2C for bps you'll see that bps is stable as
limit.

Hi, Tejun！

Do you think this *phenomenon* need to be fixed? If so, I don't see a
easy way other than throttle bio after *IO split*. Perhaps ohter than
bio merge case, this can be another motivation to move blk-throttle to
rq_qos_throttle().

Thanks,
Kuai