Re: [RFC PATCH 0/3] pm: device parallel resume mechanism

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Monday, 22 of December 2008, Zhang Rui wrote:
> Hi, rafael 

Hi,

> On Sat, 2008-12-20 at 01:15 +0800, Rafael J. Wysocki wrote:
> > On Friday, 19 of December 2008, Zhang Rui wrote:
> > > Hi, all,
> > > 
> > > The resume process can be split into 3 parts, BIOS resume time, kernel
> > > resume time and X/application resume time.
> > > And device resume takes most of the kernel resume time.
> > > this patch set introduces a new mechanism to resume device in parallel
> > > which can reduce the device resume time a lot.
> > > 
> > > In this proposal, some devices can create its own workqueue for
> > > parallel resume. And for all the other devices that depends on this
> > > device, their resume methods are queued in the same workqueue.
> > > And we flush all the workqueues before resuming X/applications.
> > > 
> > > As the devices vary from different platforms. it's hard to give an exact
> > > number of how much time it can reduce.
> > > Here are some of my test results:
> > > 1. eeepc901, kernel resume time can be reduced from about 2.1 seconds to
> > > 1.6 seconds.
> > > 2. a SantaRosa testbox, kernel resume time can be reduced from about
> > > 3.5s to 2s.
> > > 
> > > please review this patch. Any comments are welcome. :)
> > 
> > Well, given that our single-thread resume is not exactly correct,
> you mean that the current serial resume mechanism still doesn't work
> stable, right?

Not exactly.  I mean it isn't _done_ right and not working correctly is just a
consequence of this.

For this reason, we should first fix the current code and _then_ build add new
features like this, not the other way around.

> 
> >  I think it's _way_ to early to indroduce things like this.
> Right, it's not for upstream.
> But it looks good in theory, and it does works without any side effect
> in my case.
> So the patch was sent out here to see if there are some problems that
> are not covered by this patch, like the one Alan pointed out. :)

OK

Thanks,
Rafael