Re: [RFC] [PATCH] Power S3 Resume Optimization Patch. Request for Comment

Hi!

[RFC][PATCH] Power S3 Resume optimisation
Here is a simple patch for optimising the S3 resume. With this
patch the resume time is 0.85. Given the fact that device initialisation
on the resume takes almost 70% of time, By executing the whole
"device_resume()" function on a seperate kernel thread, the resume gets
completed( ie. the user can precieve) by ~0.85 sec.

Yep, but you also break it completely...

To avoid any possible race condition while processing the IO
request and to make sure all the io request are queued till the device
resume thread exits, the IO schedulars (patched cfq and as) checks a for
system_resume flag, which is set when the device resume thread starts,
if the flag is set, it doesnt put the request in the dispatch queue.
Once the flag is cleared i.e when the device resume thread is complete,
the IO-schedular behave as in normal situation.

And you noticed that, so you fixed obvious problems on block devices.
Ignoring char and net devices completely.


@@ -1088,6 +1088,19 @@
if (list_empty(&ad->fifo_list[adir]))
return 0;

+ /*
+ * Check here for the System resume flag to be cleared, if flag
is
+ * still set the resume thread hasnt completed yet, and hence
dont
+ * takeout any new request from the FIFO
+ */
+ extern int system_resuming;
+ if (system_resuming != 0)
+ {

Locking. CodingStyle.

-static void suspend_finish(suspend_state_t state)
+static int dev_resume_proc(void * data)
{
+ /* Set the global resume flag, this will be checked by the
IO_schedular

Broken mail client.

+ * before dispatching the IO request
+ */
+ system_resuming =1;

Add mdelay(1 hour) here. Then try to use your wifi card and your tv
grabber.

device_resume();
+ system_resuming = 0;
+#ifdef DEBUG
+ printk(" reseting system_resume \n");
+#endif

Pavel

--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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