Thursday, July 19, 2007

No more polling

I just committed code to hal to take advantage of asynchronous change notification events originating from SATA AN capable drives. This means we can avoid polling the drive and this should result in fewer wakeups in libata. This also opens the opportunity for the drive itself to go into a deeper sleep state when it’s not used. So all in all this should improve laptop battery life. I haven’t tried this on a laptop just yet, but when I find a suitable one I’m sure PowerTOP will tell me.

Mural at the back of 1369
I took this while testing this GPS receiver. Click to see where to get good coffee.

Credit goes to Kristen Carlson Accardi from Intel. She did the kernel bits, sent me a SATA AN capable drive and pointed me in the right direction. To try this out, you will need a recent kernel and also some patches not yet in Linus’ tree. See RH #204969 for details. I’m hoping this will make it into Fedora 8; the hal bits will for sure; for the kernel bits I suppose asking davej is in order.