Messages in this thread | | | Date | Mon, 24 Jul 2023 16:07:46 +0200 | From | Peter Zijlstra <> | Subject | Re: [RFC PATCH 0/2] Adjust CFS loadbalance to adapt QEMU CPU topology. |
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On Mon, Jul 24, 2023 at 02:57:57PM +0800, luoben@linux.alibaba.com wrote:
> > Right, why is this a problem? Hyperthreads are supposed to be symmetric, > > it doesn't matter which of the two are active, the important thing is to > > only have one active if we can. > > > > (Unlike Power7, they have asymmetric SMT) > > > > hi Peter and Vincent, > > Some upper-level monitoring logic may take the CPU usage as a metric for > computing resource scaling. Imbalanced scheduling can create the illusion > of CPU resource scarcity, leading to more frequent triggering of resource > expansion by the upper-level scheduling system. However, this is actually > a waste of resources. So, we think this may be a problem.
This is a problem of your monitoring logic -- there is absolutely no functional problem with the kernel AFAICT.
Teach the thing about SMT instead.
> Could you please take a further look at PATCH#2? We found that the default > 'nr' value did not perform well under our scenario, and we believe that > adjustable variables would be more appropriate.
That patch is tweaking default disabled code -- which we should be removing sometime soon I suppose. So no.
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