[PATCH -mm 07/14] bootmem: clean up free_all_bootmem_core

Johannes Weiner
2008-05-30T19:42:27Z

[-- Attachment #1: bootmem-cleanup-free_all_bootmem.patch --]
[-- Type: text/plain, Size: 3412 bytes --]

Rewrite the code in a more concise way using less variables.

Signed-off-by: Johannes Weiner <hannes@saeurebad.de>
CC: Ingo Molnar <mingo@elte.hu>
CC: Yinghai Lu <yhlu.kernel@gmail.com>
CC: Andi Kleen <andi@firstfloor.org>
---

mm/bootmem.c | 83 +++++++++++++++++++++++++++--------------------------------
1 file changed, 38 insertions(+), 45 deletions(-)

--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -144,66 +144,59 @@ unsigned long __init init_bootmem(unsign

static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata)
{
+ int aligned;
struct page *page;
- unsigned long pfn;
- unsigned long i, count;
- unsigned long idx, pages;
- unsigned long *map;
- int gofast = 0;
-
- BUG_ON(!bdata->node_bootmem_map);
-
- count = 0;
- /* first extant page of the node */
- pfn = PFN_DOWN(bdata->node_boot_start);
- idx = bdata->node_low_pfn - pfn;
- map = bdata->node_bootmem_map;
+ unsigned long start, end, pages, count = 0;
+
+ if (!bdata->node_bootmem_map)
+ return 0;
+
+ start = PFN_DOWN(bdata->node_boot_start);
+ end = bdata->node_low_pfn;
+
/*
- * Check if we are aligned to BITS_PER_LONG pages. If so, we might
- * be able to free page orders of that size at once.
+ * If the start is aligned to the machines wordsize, we might
+ * be able to free pages in bulks of that order.
*/
- if (!(pfn & (BITS_PER_LONG-1)))
- gofast = 1;
+ aligned = !(start & (BITS_PER_LONG - 1));
+
+ bdebug("nid=%d start=%lx end=%lx aligned=%d\n",
+ bdata - bootmem_node_data, start, end, aligned);
+
+ while (start < end) {
+ unsigned long *map, idx, vec;

- for (i = 0; i < idx; ) {
- unsigned long v = ~map[i / BITS_PER_LONG];
+ map = bdata->node_bootmem_map;
+ idx = start - PFN_DOWN(bdata->node_boot_start);
+ vec = ~map[idx / BITS_PER_LONG];

- if (gofast && v == ~0UL) {
- int order;
+ if (aligned && vec == ~0UL && start + BITS_PER_LONG < end) {
+ int order = ilog2(BITS_PER_LONG);

- page = pfn_to_page(pfn);
+ __free_pages_bootmem(pfn_to_page(start), order);
count += BITS_PER_LONG;
- order = ffs(BITS_PER_LONG) - 1;
- __free_pages_bootmem(page, order);
- i += BITS_PER_LONG;
- page += BITS_PER_LONG;
- } else if (v) {
- unsigned long m;
-
- page = pfn_to_page(pfn);
- for (m = 1; m && i < idx; m<<=1, page++, i++) {
- if (v & m) {
- count++;
+ } else {
+ unsigned long off = 0;
+
+ while (vec && off < BITS_PER_LONG) {
+ if (vec & 1) {
+ page = pfn_to_page(start + off);
__free_pages_bootmem(page, 0);
+ count++;
}
+ vec >>= 1;
+ off++;
}
- } else {
- i += BITS_PER_LONG;
}
- pfn += BITS_PER_LONG;
+ start += BITS_PER_LONG;
}

- /*
- * Now free the allocator bitmap itself, it's not
- * needed anymore:
- */
page = virt_to_page(bdata->node_bootmem_map);
pages = bdata->node_low_pfn - PFN_DOWN(bdata->node_boot_start);
- idx = bootmem_bootmap_pages(pages);
- for (i = 0; i < idx; i++, page++)
- __free_pages_bootmem(page, 0);
- count += i;
- bdata->node_bootmem_map = NULL;
+ pages = bootmem_bootmap_pages(pages);
+ count += pages;
+ while (pages--)
+ __free_pages_bootmem(page++, 0);

bdebug("nid=%d released=%ld\n", bdata - bootmem_node_data, count);