Mark Lord wrote: > I'm split on this one. For fast systems (typical notebook/desktop) it's > almost a non-issue either way. > > But a lot of media boxes will be using this code, and they tend to have > very low-power, slow-clockrate CPUs in the 200-800Mhz range, and so the > real-time hit there (from PIO) will have a much more significant impact. > > Using DMA as much as possible on those slower platforms is definitely > a plus towards avoiding non-jerky, skipped frames, or start-stoppy DVD > recording. > > Now the most intensive commands are still DMA under the proposed scheme, > so it's not those that one would be concerned with. But dropping to PIO > even for a few uncommon commands will still peg a real-time hit or two > on a slower media processor. > > So.. ???? One thing I don't understand about this argument is that PIO cycle time is not determined by CPU power. It's bound by PCI and ATA bus speed. If you put a faster CPU on the job, it just ends up wasting the same amount of time burning up more CPU cycles or am I misjudging power of those embedded CPUs? -- tejun - To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
