Hi, On Fri, 3 Dec 2010 16:28:27 +0000 Dave Martin <dave.mar...@linaro.org> wrote:
> This allows for more active power management of such functional > blocks: if the CPU is not fully loaded, you can turn them off -- the > kernel can spot when there is significant idle time and do this. If > the CPU becomes fully loaded, applications which have soft-realtime > constraints can notice this and switch to their accelerated code > (which will cause the kernel to switch the functional unit(s) on). > Or, the kernel can react to increasing CPU load by speculatively turn > it on instead. This is analogous to the behaviour of other power > governors in the system. Non-aware applications will still work > seamlessly -- these may simply run accelerated code if the hardware > supports it, causing the kernel to turn the affected functional > block(s) on. >From a power management perspective, is it really useful to load the CPU instead of using specialized units which usually provide more computing power per watt consumed ? When the CPU is idle, it can enter sleep states to save power and let a more specialized unit do the optimized work. For example, when doing video decoding, probably specialized DSPs to a much better job from a power management perspective than the CPU would do, so it's better to keep the CPU idle and let the DSP do its video decoding job. No? Thomas -- Thomas Petazzoni, Free Electrons Kernel, drivers, real-time and embedded Linux development, consulting, training and support. http://free-electrons.com _______________________________________________ linaro-toolchain mailing list linaro-toolchain@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-toolchain
