Re: [linux-pm] [RFC] Deferred disk spinup during system resume

Maksim Rayskiy
2010-12-31T00:49:30Z

>> When resuming from system suspend, scsi disks are being spun up which
>> takes quite a lot of time (5+ seconds in my case). The spinup is done
>> synchronously, so this time adds up to overall system resume time.
>> Ours is an embedded platform and we are using flash-based rootfs, so
>> there is no immediate need in harddrive after resume. What is much
>> more important for us is to minimize time-to-full-power. To speed up
>> resume, we would like to have an option to defer the spinup or run it
>> in parallel with system resume. I could not find any existing
>> mechanism to do the trick, but I might have missed something.
>>
>> Can anybody comment on this?
>
> Do you use asynchronous suspend/resume?
>

Yes, asynchronous suspend/resume is enabled - it saves about 0.5
second in my case. But resume blocks anyway because disk driver is
waiting on sd_resume() to complete.

I am wondering if we could let the resume proceed while spinup is
going on, just mark the scsi device as quiescent to block any data
transfers.

Maksim.

> Rafael
> --