[PATCH 1/4] Make usb-autosuspend timer 1 sec jiffy aligned

[PATCH 1/4] Make usb-autosuspend timer 1 sec jiffy aligned

[Venki Pallipadi]

Below are a bunch of random timers, that were active on my system,
that can better be round_jiffies() aligned.

I guess we need a audit of all timer usages atleast in kernel-core.

This patch:

Make usb autosuspend timers 1sec jiffy aligned.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>

Index: linux-2.6.22-rc-mm/drivers/usb/core/driver.c
===================================================================
--- linux-2.6.22-rc-mm.orig/drivers/usb/core/driver.c	2007-05-24 11:16:00.000000000 -0700
+++ linux-2.6.22-rc-mm/drivers/usb/core/driver.c	2007-05-25 10:00:50.000000000 -0700
@@ -974,7 +974,7 @@
 			 * or for the past.
 			 */
 			queue_delayed_work(ksuspend_usb_wq, &udev->autosuspend,
-					suspend_time - jiffies);
+				round_jiffies_relative(suspend_time - jiffies));
 			}
 		return -EAGAIN;
 	}

Re: [PATCH 1/4] Make usb-autosuspend timer 1 sec jiffy aligned

[Randy Dunlap]

On Tue, 29 May 2007 10:58:21 -0700 Venki Pallipadi wrote:

> 
> 
> Below are a bunch of random timers, that were active on my system,
> that can better be round_jiffies() aligned.

and these 4 patches help with (a) power usage, or (b) cache
usage/niceness, or (c) other (be specific)...

Thanks.

> I guess we need a audit of all timer usages atleast in kernel-core.
> 
> This patch:
> 
> Make usb autosuspend timers 1sec jiffy aligned.
> 
> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
> 
> Index: linux-2.6.22-rc-mm/drivers/usb/core/driver.c
> ===================================================================
> --- linux-2.6.22-rc-mm.orig/drivers/usb/core/driver.c	2007-05-24 11:16:00.000000000 -0700
> +++ linux-2.6.22-rc-mm/drivers/usb/core/driver.c	2007-05-25 10:00:50.000000000 -0700
> @@ -974,7 +974,7 @@
>  			 * or for the past.
>  			 */
>  			queue_delayed_work(ksuspend_usb_wq, &udev->autosuspend,
> -					suspend_time - jiffies);
> +				round_jiffies_relative(suspend_time - jiffies));
>  			}
>  		return -EAGAIN;
>  	}
> -

---
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***

Re: [PATCH 1/4] Make usb-autosuspend timer 1 sec jiffy aligned

[Venki Pallipadi]

On Tue, May 29, 2007 at 11:22:30AM -0700, Randy Dunlap wrote:
> On Tue, 29 May 2007 10:58:21 -0700 Venki Pallipadi wrote:
> 
> > 
> > 
> > Below are a bunch of random timers, that were active on my system,
> > that can better be round_jiffies() aligned.
> 
> and these 4 patches help with (a) power usage, or (b) cache
> usage/niceness, or (c) other (be specific)...
> 

Yes. They are all related to power savings with tickless kernel.
A 5 sec timer account for 0.2 unnecessary wakeups per sec (powertop numbers).
All these patches together account for somewhere between 0.5-1
wakeup per second saving. That means my wakeups per second
comes down from ~18 per second to ~17 per second.
On my dual core laptop, CPUs will have more than 3% increase in
average C3 residency (actual powertop number went from ~104mS to ~108mS
long term C3 residency).

The actual AC power numbers were not consisitent enough to be reported here.
But, all these small changes will add up in terms of power savings and
battery life.

Thanks,
Venki