data · CC BY 4.0 · v1.0
SMC CPU power rails vs IOReport CPU Energy calibration (Mac17,8, macOS 27)
Six SMC CPU power rails against IOReport CPU Energy over four publication spans: ratios 0.896 to 0.997.
about
What this is
A 202 s capture (760 rows, one about every 0.27 s) on a MacBook Pro Mac17,8 (Apple M5 Pro), macOS 27.0 (26A428), without sudo, on 2026-09-23, through idle and an 18-thread load. Each row holds the IOReport CPU Energy running total and its driver timestamp, the GPU Energy total, and eleven SMC power keys in watts, including the six CPU rails PP0b, PP4b, PP1b, PP7b, PR0b and PR7b and the system figure PSTR. For every complete publication span of CPU Energy, the spans table compares the IOReport rate (energy over the driver's own window) with the mean of the rail sum over the same span. Over the four complete spans (94.3, 27.3, 12.8 and 2.2 s) the rails read 0.989, 0.947, 0.896 and 0.997 of the IOReport figure: slightly low, never high. A fifth, partial span is included and flagged, because the capture began 14.2 s into it. The rail mapping is undocumented by Apple and applies to the Mac17,8 only.
Captured 2026-09-23 to 2026-09-24. Method: AppleSMC user client reads (flt keys, watts), no sudo; IOReport Energy Model CPU Energy with the RawElements driver timestamp; Rate over the driver publication window compared with the mean SMC rail sum over the same window. Full notes: README.md.
Used by: the macOS 27 post.
files
Files
| File | Rows | Size | SHA-256 |
|---|---|---|---|
| spans.csv One row per CPU Energy publication span: IOReport rate, mean rail sum, ratio. | 5 | 620 B | 6953e5e8c8fc20102128e0f9dc649fe4ad0d6d311ad425347d5b9516e41d3ac7 |
| samples.csv One row per sample: IOReport totals, driver timestamp and eleven SMC power keys. | 760 | 135.6 KB | 87517a5021330afa546ae010efbdab53489750d2c8ad4fc257b641cc9909ff5d |
columns
Variables
ioreport_cpu_w(W)- IOReport CPU Energy over a publication span divided by the span.
smc_rail_sum_mean_w(W)- Mean of PP0b + PP4b + PP1b + PP7b + PR0b + PR7b over the same span.
ratio_rails_to_ioreport(ratio)- smc_rail_sum_mean_w divided by ioreport_cpu_w.
smc_pstr_w(W)- SMC PSTR, total system power.
licence
Cite and reuse
Licensed CC BY 4.0: reuse it anywhere, with credit.
Sheth, L. (2026). SMC CPU power rails vs IOReport CPU Energy calibration (Mac17,8, macOS 27) (Version 1.0) [Data set]. plottypus.com. https://plottypus.com/data/smc-rails-calibration