Re: [RFC/PATCH] Deferred disk spinup during system resume

[Jeff Garzik <jgarzik@pobox.com>]

On 01/19/2011 03:29 PM, Maksim Rayskiy wrote:
>> A kernel modification might not even be needed.
>>
>> Have you tried simply issuing READ VERIFY via bsg, and not caring if it
>> completes?  bsg should be able to handle an app submitting a command, but
>> never checking the 'done' list, right?  A simple shell app could execute
>>
>>         write(bsg_fd, ... SCSI READ VERIFY command ...)
>>         exit(0)
>>
>> to avoid waiting for READ VERIFY command completion, I would hope.
>>
>>         Jeff
>>
>
> My question was how to speed up system resume when he the spinup
> request is coming from sd_resume(). For shell method to work I would
> have to ignore this request entirely and do READ VERIFY when system is
> fully restored.
> Can it be done without kernel modification? Tejun mentioned using
> manage_start_stop flag but had some reservations against it.

Oh, if we're talking about sd_resume(), SCSI definitely has an internal 
mechanism to fire off a request, without blocking and waiting for a 
response.  It does sound like a kernel modification, but it should be 
straightforward via existing APIs.

	Jeff