On Fri, Aug 03 2007, Jeff Garzik wrote: > * Kristen: ALPM patches. We definitely want them, as they save a ton of > power. The problem with ALPM, as I see it, is that it is way too aggressive. It really needs to be combined with a timer to be useful, it's really a huge shame that it doesn't come equipped with a timeout setting in hardware. Lacking that, we could punt to using a second aligned timer that just checks for activity in the last second, and if none was seen then enable ALPM. That should have absolutely minimal impact on CPU consumption. Likewise for when we see IO, when the rate/sec goes beyond a low threshold then disable ALPM again. In my testing on this notebook (x60), throughput was reduced to about 30% when using ALPM. So while it does save a good amount of power, it also makes the disk a slow dog if you are actually using it. -- Jens Axboe - 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
