Re: [PATCH]: Speed freeing memory for suspend.

[Nigel Cunningham <ncunningham@cyclades.com>]

Hi.

Here are the stats:

1GB P4, 2.6.11+Suspend2 2.1.8.
Soft image size limit set to 2MB to emulate Pavel's implementation (eat
as much memory as we can).

Without patch:
Freed  16545 pages in  4000 jiffies = 16.16 MB/s
Freed  83281 pages in 14060 jiffies = 23.14 MB/s
Freed 237754 pages in 41482 jiffies = 22.39 MB/s

With patch:
Freed  52257 pages in  6700 jiffies = 30.46 MB/s
Freed 105693 pages in 11035 jiffies = 37.41 MB/s
Freed 239007 pages in 18284 jiffies = 51.06 MB/s

With a less aggressive image size limit (200MB):

Without the patch:
Freed  14600 pages in  1749 jiffies = 32.61 MB/s (Anomolous!)
Freed  88563 pages in 14719 jiffies = 23.50 MB/s
Freed 205734 pages in 32389 jiffies = 24.81 MB/s

With the patch:
Freed  68252 pages in   496 jiffies = 537.52 MB/s
Freed 116464 pages in   569 jiffies = 798.54 MB/s
Freed 209699 pages in   705 jiffies = 1161.89 MB/s

The later pages take more work to get, which accounts for the slower
MB/s with smaller numbers of pages to free. Without the patch, though,
getting the easier pages also takes longer because we do a far greater
number of invocations of shrink_all_memory in order to get the same
number of pages.

Regards,

Nigel

On Thu, 2005-03-03 at 22:26, Andrew Morton wrote: 
> Nigel Cunningham <ncunningham@cyclades.com> wrote:
> >
> > Here's a patch I've prepared which improves the speed at which memory is
> >  freed prior to suspend. It should be a big gain for swsusp.
> 
> Patch is simple enough but, as always, please back up an optimization patch
> with quantitative test results.



-- 
Nigel Cunningham
Software Engineer, Canberra, Australia
http://www.cyclades.com
Bus: +61 (2) 6291 9554; Hme: +61 (2) 6292 8028;  Mob: +61 (417) 100 574

Maintainer of Suspend2 Kernel Patches http://softwaresuspend.berlios.de