Re: [RFC/RFT][PATCH -mm] swsusp: improve memory shrinking

[Rafael J. Wysocki]

On Monday 27 February 2006 00:32, Rafael J. Wysocki wrote:
> On Sunday 26 February 2006 19:53, Pavel Machek wrote:
> > > > > > I did try shrink_all_memory() five times, with .5 second delay between
> > > > > > them, and it freed more memory at later tries.
> > > > > 
> > > > > I wonder if the delays are essential or if so, whether they may be shorter
> > > > > than .5 sec.
> > > > 
> > > > I was using this with some success... (Warning, against old
> > > > kernel). But, as I said, I consider it ugly, and it would be better to
> > > > fix shrink_all_memory.
> > > 
> > > Appended is a patch against the current -mm.
> > >   [It also makes
> > > swsusp_shrink_memory() behave as documented for image_size = 0.
> > > Currently, if it states there's enough free RAM to suspend, it won't bother
> > > to free a single page.]
> > 
> > Could we get bugfix part separately?
> 
> Sure.  Appended is the bugfix (I haven't tested it separately yet, but I think
> it's simple enough) ...

... and this is the workaround of the "shrink_all_memory() returns 0 prematurely"
problem (not tested separately yet).  [Together these patches make my box
actually free more memory when image_size = 0.]

---
Make swsusp_shrink_memory() try harder to free more RAM if necessary or
if the anticipated size of the image is greater than image_size.


Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>
---
 kernel/power/swsusp.c |   13 +++++++++++--
 1 files changed, 11 insertions(+), 2 deletions(-)

Index: linux-2.6.16-rc4-mm2/kernel/power/swsusp.c
===================================================================
--- linux-2.6.16-rc4-mm2.orig/kernel/power/swsusp.c	2006-02-27 00:25:34.000000000 +0100
+++ linux-2.6.16-rc4-mm2/kernel/power/swsusp.c	2006-02-27 00:28:58.000000000 +0100
@@ -175,6 +175,8 @@ void free_all_swap_pages(int swap, struc
  */
 
 #define SHRINK_BITE	10000
+#define SHRINK_RETRY	3
+#define SHRINK_SLEEP	100
 
 int swsusp_shrink_memory(void)
 {
@@ -182,6 +184,7 @@ int swsusp_shrink_memory(void)
 	struct zone *zone;
 	unsigned long pages = 0;
 	unsigned int i = 0;
+	int retry = SHRINK_RETRY;
 	char *p = "-\\|/";
 
 	printk("Shrinking memory...  ");
@@ -200,8 +203,14 @@ int swsusp_shrink_memory(void)
 			if (freed > 0) {
 				pages += freed;
 				tmp = freed;
-			} else if (tmp > 0) {
-				return -ENOMEM;
+				retry = SHRINK_RETRY;
+			} else {
+				if (--retry) {
+					msleep_interruptible(SHRINK_SLEEP);
+					tmp = size;
+				} else if (tmp > 0) {
+					return -ENOMEM;
+				}
 			}
 		}
 		printk("\b%c", p[i++%4]);
-
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