Messages in this thread | | | Date | Wed, 8 Feb 2023 14:43:45 +0100 | From | Jan Kara <> | Subject | Re: [PATCH] blk-ioprio: Introduce promote-to-rt policy |
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On Fri 03-02-23 11:45:32, Bart Van Assche wrote: > On 2/2/23 17:48, Hou Tao wrote: > > I don't get it on how to remove IOPRIO_POL_PROMOTION when calculating the final > > ioprio for bio. IOPRIO_POL_PROMOTION is not used for IOPRIO_CLASS values but > > used to determinate on how to calculate the final ioprio for bio: choosing the > > maximum or minimum between blkcg ioprio and original bio bi_ioprio. > > Do the block layer code changes shown below implement the functionality > that you need?
Just one question guys: So with my a78418e6a04c ("block: Always initialize bio IO priority on submit") none-to-rt policy became effectively a noop as Hou properly noticed. Are we aware of any users that were broken by this? Shouldn't we rather fix the code so that none-to-rt starts to operate correctly again? Or maybe change the none-to-rt meaning to be actually promote-to-rt?
I have to admit I'm wondering a bit what was the intended usecase behind the introduction of none-to-rt policy. Can someone elaborate? promote-to-rt makes some sense to me - we have a priviledged cgroup we want to provide low latency access to IO but none-to-rt just does not make much sense to me...
Honza -- Jan Kara <jack@suse.com> SUSE Labs, CR
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