Re: syncing the disks when entering sleep

Nigel Cunningham
2010-01-22T21:31:46Z

Hi.

Rafael J. Wysocki wrote:
> On Friday 22 January 2010, Leisner, Martin wrote:
>> I noticed when we enter sleep states, it seems there's always a
>> sys_sync given.
>>
>> When having an embedded system doing WOL (already in laptop mode to
>> cache
>> all the writes), it reasonable to wake up dozens of times of day and
>> quickly go back to sleep. If the disk is not spun up,
>> and there's some work to be done, won't the sys_sync spin up the disk
>> before going to sleep?
>>
>> It would be good to have a knob (in /sys) you can tweak from usespace to
>>
>> configure the behavior of whether you want to do a sync when entering
>> sleep.
>>
>> The ideal behavior would be:
>>
>> if(disk is spun up)
>> then let the sync happen
>
> I'm not against that. Patch welcome. :-)

Oooh. I am. That's providing potential for unpredictable behaviour. Much
better IMO would be providing a tuning know that explicitly and
unconditionally disables syncing.

Regards,

Nigel