Re: Page cache write performance issue

[Andrew Morton]

Nathan Scott <nathans@xxxxxxx> wrote:
>
>  So, any ideas what happened to 2.6.9?

Does reverting the below fix it up?

>   Whats the rationale for commencing writeout earlier in 2.6
> (even when there's
>  so much free memory available)?

There wasn't much rationale behind that patch - that's why I dropped it the
first three times ;)  I have no problem with making it four times.

It could be that small values of unmapped_ratio are making background_ratio
too small.


--- a/mm/page-writeback.c	10 Aug 2004 04:16:17 -0000	1.43
+++ a/mm/page-writeback.c	13 Oct 2004 06:12:03 -0000
@@ -153,9 +153,11 @@
 	if (dirty_ratio < 5)
 		dirty_ratio = 5;
 
-	background_ratio = dirty_background_ratio;
-	if (background_ratio >= dirty_ratio)
-		background_ratio = dirty_ratio / 2;
+	/*
+	 * Keep the ratio between dirty_ratio and background_ratio roughly
+	 * what the sysctls are after dirty_ratio has been scaled (above).
+	 */
+	background_ratio = dirty_background_ratio * dirty_ratio/vm_dirty_ratio;
 
 	background = (background_ratio * total_pages) / 100;
 	dirty = (dirty_ratio * total_pages) / 100;

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/