The advantage of stress-ng is that it's easy to make it run with specific CPU utilization numbers. The tests where I run some number of workers at 100% utilization are interesting since they give such perfect graphs, but I think the version where I have 24 workers and increase their utilization slowly is more realistic for showing how production CPU utilization changes.

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BrendanLong 6 days ago | parent [-]

Fun data point though, I just ran three data points of the Phoronix nginx benchmark and got these results:

- Pinned to 6 cores: 28k QPS

- Pinned to 12 cores: 56k QPS

- All 24 cores: 62k QPS

I'm not sure how this applies to realistic workloads where you're using all of the cores but not maxing them out, but it looks like hyperthreading only adds ~10% performance in this case.

	▲	BrendanLong 4 days ago \| parent \| next [-]
		Here's results of the Nginx benchmark pinned to 1-24 cores: https://docs.google.com/spreadsheets/d/1d_OK_ckLT1zTA_fG4vkq... At 51% reported CPU utilization, it's doing about 80% of the maximum requests per second, and it can't get above 80% utilization. I also added a section: https://www.brendanlong.com/cpu-utilization-is-a-lie.html#bo...
	▲	PunchyHamster 6 days ago \| parent \| prev \| next [-]
		I'd imagine in this case it's just uncounted usage from OS networking stack
	▲	justsomehnguy 6 days ago \| parent \| prev [-]
		You missed to try 18 cores.