[Xen-ia64-devel] [patch] small speedup to boot allocator

[Jes Sorensen <jes@xxxxxxx>]

Hi,

This is a small speedup, but I think it's a good thing to do<tm>.

Jes

Small speedup for the boot allocator to avoid it scanning through a
space which is known to be empty.

Signed-off-by: Jes Sorensen <jes@xxxxxxx>


diff -r 7b250cf49e50 xen/common/page_alloc.c
--- a/xen/common/page_alloc.c   Sun Sep 24 14:55:57 2006 -0600
+++ b/xen/common/page_alloc.c   Mon Sep 25 18:47:57 2006 +0200
@@ -112,6 +117,7 @@ static void map_alloc(unsigned long firs
     }
 }
 
+static unsigned long first_pg = -1UL;
 
 static void map_free(unsigned long first_page, unsigned long nr_pages)
 {
@@ -128,6 +134,10 @@ static void map_free(unsigned long first
     start_off = first_page & (PAGES_PER_MAPWORD-1);
     end_idx   = (first_page + nr_pages) / PAGES_PER_MAPWORD;
     end_off   = (first_page + nr_pages) & (PAGES_PER_MAPWORD-1);
+
+    if (curr_idx < first_pg)
+        first_pg = curr_idx;
+
 
     if ( curr_idx == end_idx )
     {
@@ -217,7 +229,7 @@ unsigned long alloc_boot_pages(unsigned 
 {
     unsigned long pg, i;
 
-    for ( pg = 0; (pg + nr_pfns) < max_page; pg += pfn_align )
+    for ( pg = first_pg; (pg + nr_pfns) < max_page; pg += pfn_align )
     {
         for ( i = 0; i < nr_pfns; i++ )
             if ( allocated_in_map(pg + i) )

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