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SubjectRe: [PATCH V3 00/11] block-throttle: add .high limit

> Il giorno 04 ott 2016, alle ore 20:54, Tejun Heo <> ha scritto:
> Hello, Paolo.
> On Tue, Oct 04, 2016 at 07:43:48PM +0200, Paolo Valente wrote:
>>> I don't think IO bandwidth does not matter. The problem is bandwidth can't
>>> measure IO cost. For example, you can't say 8k IO costs 2x IO resource than 4k
>>> IO.
>> For what goal do you need to be able to say this, once you succeeded
>> in guaranteeing bandwidth and low latency to each
>> process/client/group/node/user?
> For resource partitioning mostly. It's not a single user or purpose
> use case. The same device gets shared across unrelated workloads and
> we need to guarantee differing levels of quality of service to each
> regardless of the specifics of workload.

That's exactly what BFQ has succeeded in doing in all the tests
devised so far. Can you give me a concrete example for which I can
try with BFQ and with any other mechanism you deem better. If
you are right, numbers will just make your point.


> We actually need to be able
> to control IO resources.

> Thanks.
> --
> tejun

Paolo Valente
Dipartimento di Scienze Fisiche, Informatiche e Matematiche
Via Campi 213/B
41125 Modena - Italy

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