Re: [PATCH 0/7] introduce cpu.headroom knob to cpu controller

From: Michal Koutný
Date: Tue May 21 2019 - 09:50:08 EST


Hello Song.

On Wed, Apr 10, 2019 at 07:43:35PM +0000, Song Liu <songliubraving@xxxxxx> wrote:
> The load level above is measured as requests-per-second.
>
> When there is no side workload, the system has about 45% busy CPU with
> load level of 1.0; and about 75% busy CPU at load level of 1.5.
>
> The saturation starts before the system hitting 100% utilization. This is
> true for many different resources: ALUs in SMT systems, cache lines,
> memory bandwidths, etc.
I have read through the thread continuation and it appears to me there
is some misunderstanding on the latency metric (scheduler latency <=
your latency <= request wall time?).

Could you please describe how is the latency that you report defined and
measured?

Thanks,
Michal

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