[Xen-changelog] [xen-unstable] [XEN] Boot allocator searches from earliest registered

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Node ID c3ff06093028962ffb64af4ef62693d6dc3525a2
# Parent  21609e7f5a49a30c2d8ec978148a2317ad70bd0e
[XEN] Boot allocator searches from earliest registered
memory region instead of 0.

Based on a patch from Jes Sorensen <jes@xxxxxxx> which
massively improves boot time on SGI Altix systems.

Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
---
 xen/common/page_alloc.c |   46 +++++++++++++++++++++++++---------------------
 1 files changed, 25 insertions(+), 21 deletions(-)

diff -r 21609e7f5a49 -r c3ff06093028 xen/common/page_alloc.c
--- a/xen/common/page_alloc.c   Thu Dec 14 11:39:40 2006 +0000
+++ b/xen/common/page_alloc.c   Thu Dec 14 12:02:30 2006 +0000
@@ -136,7 +136,6 @@ static void map_alloc(unsigned long firs
     }
 }
 
-
 static void map_free(unsigned long first_page, unsigned long nr_pages)
 {
     unsigned long start_off, end_off, curr_idx, end_idx;
@@ -170,6 +169,8 @@ static void map_free(unsigned long first
 /*************************
  * BOOT-TIME ALLOCATOR
  */
+
+static unsigned long first_valid_mfn = ~0UL;
 
 /* Initialise allocator to handle up to @max_page pages. */
 paddr_t init_boot_allocator(paddr_t bitmap_start)
@@ -203,6 +204,8 @@ void init_boot_pages(paddr_t ps, paddr_t
     if ( pe <= ps )
         return;
 
+    first_valid_mfn = min_t(unsigned long, ps >> PAGE_SHIFT, first_valid_mfn);
+
     map_free(ps >> PAGE_SHIFT, (pe - ps) >> PAGE_SHIFT);
 
     /* Check new pages against the bad-page list. */
@@ -256,16 +259,17 @@ unsigned long alloc_boot_pages_at(unsign
 
 unsigned long alloc_boot_pages(unsigned long nr_pfns, unsigned long pfn_align)
 {
-    unsigned long pg, i = 0;
-
-    for ( pg = 0; (pg + nr_pfns) < max_page; pg += pfn_align )
-    {
-        i = alloc_boot_pages_at(nr_pfns, pg);
-        if (i != 0)
+    unsigned long pg;
+
+    pg = first_valid_mfn & ~(pfn_align-1);
+    while ( (pg + nr_pfns) < max_page )
+    {
+        if ( alloc_boot_pages_at(nr_pfns, pg) != 0 )
             break;
-    }
-
-    return i;
+        pg += pfn_align;
+    }
+
+    return pg;
 }
 
 
@@ -301,7 +305,7 @@ void end_boot_allocator(void)
                 INIT_LIST_HEAD(&heap[i][j][k]);
 
     /* Pages that are free now go to the domain sub-allocator. */
-    for ( i = 0; i < max_page; i++ )
+    for ( i = first_valid_mfn; i < max_page; i++ )
     {
         curr_free = next_free;
         next_free = !allocated_in_map(i+1);
@@ -324,7 +328,7 @@ void init_heap_pages(
 void init_heap_pages(
     unsigned int zone, struct page_info *pg, unsigned long nr_pages)
 {
-    unsigned int nid_curr,nid_prev;
+    unsigned int nid_curr, nid_prev;
     unsigned long i;
 
     ASSERT(zone < NR_ZONES);
@@ -478,37 +482,37 @@ void scrub_heap_pages(void)
 void scrub_heap_pages(void)
 {
     void *p;
-    unsigned long pfn;
+    unsigned long mfn;
 
     printk("Scrubbing Free RAM: ");
 
-    for ( pfn = 0; pfn < max_page; pfn++ )
+    for ( mfn = first_valid_mfn; mfn < max_page; mfn++ )
     {
         /* Every 100MB, print a progress dot. */
-        if ( (pfn % ((100*1024*1024)/PAGE_SIZE)) == 0 )
+        if ( (mfn % ((100*1024*1024)/PAGE_SIZE)) == 0 )
             printk(".");
 
         process_pending_timers();
 
         /* Quick lock-free check. */
-        if ( allocated_in_map(pfn) )
+        if ( allocated_in_map(mfn) )
             continue;
 
         spin_lock_irq(&heap_lock);
 
         /* Re-check page status with lock held. */
-        if ( !allocated_in_map(pfn) )
-        {
-            if ( IS_XEN_HEAP_FRAME(mfn_to_page(pfn)) )
+        if ( !allocated_in_map(mfn) )
+        {
+            if ( IS_XEN_HEAP_FRAME(mfn_to_page(mfn)) )
             {
-                p = page_to_virt(mfn_to_page(pfn));
+                p = page_to_virt(mfn_to_page(mfn));
                 memguard_unguard_range(p, PAGE_SIZE);
                 clear_page(p);
                 memguard_guard_range(p, PAGE_SIZE);
             }
             else
             {
-                p = map_domain_page(pfn);
+                p = map_domain_page(mfn);
                 clear_page(p);
                 unmap_domain_page(p);
             }

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