Re: BFQ cgroup weights range

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 




> 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





[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Security]     [Bugtraq]     [Linux OMAP]     [Linux MIPS]     [eCos]     [Asterisk Internet PBX]     [Linux API]     [Monitors]

  Powered by Linux