> Il giorno 26 ago 2021, alle ore 19:25, Tejun Heo <tj@xxxxxxxxxx> ha scritto:
>
> On Thu, Aug 26, 2021 at 03:12:12PM +0200, Michal Koutný wrote:
>> On Tue, Aug 24, 2021 at 02:51:47PM +0200, Paolo Valente <paolo.valente@xxxxxxxxxx> wrote:
>>> BFQ inherited these constants when we forked it from CFQ. I'm ok with
>>> increasing max weight to 10000. I only wonder whether this would
>>> break some configuration, as the currently maximum weight would not be
>>> the maximum weight any longer.
>>
>> Thanks for the reply. Let me form the idea as a patch (and commit
>> message) and discuss based on that if needed (+ccrosspost into cgroups
>> ML).
>>
>> -- >8 --
>> From: Michal Koutný <mkoutny@xxxxxxxx>
>> Subject: [PATCH] block, bfq: Accept symmetric weight adjustments
>>
>> The allowed range for BFQ weights is currently 1..1000 with 100 being
>> the default. There is no apparent reason to not accept weight
>> adjustments of same ratio on both sides of the default. This change
>> makes the attribute domain consistent with other cgroup (v2) knobs with
>> the weight semantics.
>>
>> This extension of the range does not restrict existing configurations
>> (quite the opposite). This may affect setups where weights >1000 were
>> attempted to be set but failed with the default 100. Such cgroups would
>> attain their intended weight now. This is a changed behavior but it
>> rectifies the situation (similar intention to the commit 69d7fde5909b
>> ("blkcg: use CGROUP_WEIGHT_* scale for io.weight on the unified
>> hierarchy") for CFQ formerly (and v2 only)).
>>
>> Additionally, the changed range does not imply all IO workloads can be
>> really controlled to achieve the widest possible ratio 1:10^4.
>>
>> Signed-off-by: Michal Koutný <mkoutny@xxxxxxxx>
>
> Looks fine to me.
>
> Acked-by: Tejun Heo <tj@xxxxxxxxxx>
>
Acked-by: Paolo Valente <paolo.valente@xxxxxxxxxx>
Thanks for this improvement,
Paolo
> Thanks.
>
> --
> tejun
