4 ms·
What's a straightforward way to clock down a CPU to a fixed rate? I sometimes want to run benchmarks and I'd like my laptop to stick to one speed I understand
by geokon 5y ago
What's a straightforward way to clock down a CPU to a fixed rate?
I sometimes want to run benchmarks and I'd like my laptop to stick to one speed
I understand it's a bit problematic with the latest CPUs bc the gap between turbo and non turbo is so huge - and the CPU is in turbo a good chunk of the time (and your cache performance will be very different running at 1Ghz vs 4Ghz)
Anyone have a good solution?
- marcan_42 5y agoChange the cpufreq governor to userspace and then you can echo the desired frequency into its control file. It will stick.
- baybal2 5y ago> the gap between turbo and non turbo is so huge > Anyone have a good solution? A good cooler ---- Downvotes, really? There is really no trick around thermals being the main performance limiting factor for the last 10 years, since CPUs started coming with hardware "turbo" You cannot optimise around that.
- geokon 5y agoYeah but that's prolly not really a solution either (sidestepped the issue of modifying the cooler on a laptop). Bc you can't lock yourself to always be in turbo. So you can't get consistent performance while benchmarking
- baybal2 5y agoThe problem is not understood by the prime majority: As said above, the performance, and power consumption of modern CPUs is an "all, or nothing" choice. Modern laptop CPUs are nothing, but well disguised desktop/server cores. Nobody designs designated mobile use cores, unless you are in ARM world. In principle, they are unable to work in the "middle gear." CPU makers tried to make them to, but never managed to get a reasonable trade off. So you cannot run them reasonably at "half-performance"
- timpattinson 5y agoYou're missing the point really. With a competent desktop cpu/mobo it's easy to peg the CPU clock at a certain frequency. And with modern CPUs the power density is sufficently high that the die and heatspreader thermal resistance is enough to cause substantial temperature changes even with completely overspecced cooling.
- baybal2 5y ago> With a competent desktop cpu/mobo it's easy to peg the CPU clock at a certain frequency. No, you can up/down the base/turbo limits, but the effect will be miniscule.
- jeffbee 5y agoI just use ‘cpupower frequency-set’ to pin cores at their base clock speed for microbenchmarking.