On Wed, 9 Dec 2009, Linus Torvalds wrote: > That's partly why I realy did suggest that we do the async stuff purely in > the USB layer, rather than try to put it deeper in the device layer. And > if we do support it "natively" in the device layer like Rafael's latest > patch, I still think we should be very very nervous about making devices > async unless there is a measured - and very noticeable - advantage. Agreed. Arjan's measurements indicated that USB was one of the biggest offenders; everything else other than the PS/2 mouse was much faster. Given these results there isn't much incentive to do anything else asynchronously. (However other devices not present on Arjan's machine may be a different story. Spinning up multiple external disks is a good example -- although here it may be necessary for the driver to take charge, because spinning up a disk requires a lot of power and doing too many of them at the same time could be bad.) Alan Stern _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
