On Fri, 17 Jan 2014, Dan Williams wrote: > Once dpm_resume of the disk is asynchronous, is there much incremental > gain by further deferring spin up? The drawback of doing on-demand > resume of the disk is that you incur the full resume latency right > when you need the data. System resume is a strong hint to warm the > disks back up, and they will go back to sleep if unused. > > Of course it reduces the power savings if dpm_suspend/resume is a > frequent occurrence. However, are systems that make aggressive use of > system suspend shipping with rotating media, or do they ship with > disks that are cheap to resume? If suspend is not frequent I wonder > if it is worth the trouble/latency cost to keep the disk(s) asleep.
You will have to argue this point with Phillip. If necessary, we could add a sysfs attribute to force a spin-up during system resume. Or you could disable runtime PM for the disk, but that has its own disadvantages. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
