Re: [PATCH V2 0/7] block: improve iops limit throttle

[Ming Lei <ming.lei@redhat.com>]

On Wed, Feb 09, 2022 at 05:14:22PM +0800, Ming Lei wrote:
> Hello Guys,
> 
> Lining reported that iops limit throttle doesn't work on dm-thin, also
> iops limit throttle works bad on plain disk in case of excessive split.
> 
> Commit 4f1e9630afe6 ("blk-throtl: optimize IOPS throttle for large IO scenarios")
> was for addressing this issue, but the taken approach is just to run
> post-accounting, then current split bios won't be throttled actually,
> so actual iops throttle result isn't good in case of excessive bio
> splitting.
> 
> The 1st three patches are cleanup.
> 
> The 4th patches add one new local helper of submit_bio_noacct_nocheck() for
> blk_throtl_dispatch_work_fn(), so that bios won't be throttled any more
> when blk-throttle code dispatches throttled bios.
> 
> The 5th and 6th patch makes the real difference for throttling split bio wrt.
> iops limit.
> 
> The last patch is to revert commit 4f1e9630afe6 ("blk-throtl: optimize IOPS
> throttle for large IO scenarios").
> 
> Lining has verified that iops throttle is improved much on the posted
> RFC V1 version.
> 
> V2:
> 	- remove RFC
> 	- don't add/export __submit_bio_noacct(), instead add one new local
> 	helper of submit_bio_noacct_nocheck() per Christoph's suggestion
> 
> Ming Lei (7):
>   block: move submit_bio_checks() into submit_bio_noacct
>   block: move blk_crypto_bio_prep() out of blk-mq.c
>   block: don't declare submit_bio_checks in local header
>   block: don't check bio in blk_throtl_dispatch_work_fn
>   block: throttle split bio in case of iops limit
>   block: don't try to throttle split bio if iops limit isn't set
>   block: revert 4f1e9630afe6 ("blk-throtl: optimize IOPS throttle for
>     large IO scenarios")

Hello Tejun, Chunguang and guys,

Can you give an review on this patchset? Especially the last 4 changes
on blk-throtl?


Thanks,
Ming