[OLPC-devel] Thoughts on S3 resume.

[Jim Gettys]

On Thu, 2006-08-10 at 21:58 +0100, Chris Ball wrote:

> Yes, that's what CONFIG_PRINTK_TIME does.  Here's a log with that
> enabled (and with the IDE driver unloaded).  The delay is happening
> before the first ("Back to C!") kernel message, with the rest of the
> resume being fairly expedient:
> 
> - 120ms: report BUG()
> - 10ms: "Finishing wakeup" (driver resumption)
> - 30ms: Restarting tasks, thawing cpus
> 
> If we can lose the twenty-second delay and most of the time spent in the
> BUG() path, things are looking very good indeed.  First things first,
> though; I'll look at debugging wakeup.S, since we spend time there
> before the kernel messages.  Matthew, any thoughts?

That's definitely encouraging.

Thanks for the data.

Looks like avoiding ACPI entirely will help loads (as expected).

Stopping tasks is taking a while on suspend, and will be worth looking
at.

The Platform i8042 to Restarting tasks is also significant at 25ms.
                              - Jim

-- 
Jim Gettys
One Laptop Per Child