bootmem: clean up alloc_bootmem_core
alloc_bootmem_core has become quite nasty to read over time. This is a
clean rewrite that keeps the semantics.
bdata->last_pos has been dropped.
bdata->last_success has been renamed to hint_idx and it is now an index
relative to the node's range. Since further block searching might start
at this index, it is now set to the end of a succeeded allocation rather
than its beginning.
bdata->last_offset has been renamed to last_end_off to be more clear that
it represents the ending address of the last allocation relative to the
node.
[y-goto@jp.fujitsu.com: fix new alloc_bootmem_core()]
Signed-off-by: Johannes Weiner <hannes@saeurebad.de>
Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/bootmem.h b/include/linux/bootmem.h
index 5000fd7..90921d10 100644
--- a/include/linux/bootmem.h
+++ b/include/linux/bootmem.h
@@ -31,10 +31,8 @@
unsigned long node_boot_start;
unsigned long node_low_pfn;
void *node_bootmem_map;
- unsigned long last_offset;
- unsigned long last_pos;
- unsigned long last_success; /* Previous allocation point. To speed
- * up searching */
+ unsigned long last_end_off;
+ unsigned long hint_idx;
struct list_head list;
} bootmem_data_t;
diff --git a/mm/bootmem.c b/mm/bootmem.c
index 300d126..94ea612 100644
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -242,8 +242,9 @@
* considered reserved.
*/
- if (addr >= bdata->node_boot_start && addr < bdata->last_success)
- bdata->last_success = addr;
+ if (addr >= bdata->node_boot_start &&
+ PFN_DOWN(addr - bdata->node_boot_start) < bdata->hint_idx)
+ bdata->hint_idx = PFN_DOWN(addr - bdata->node_boot_start);
/*
* Round up to index to the range.
@@ -431,36 +432,16 @@
}
#endif /* !CONFIG_HAVE_ARCH_BOOTMEM_NODE */
-/*
- * We 'merge' subsequent allocations to save space. We might 'lose'
- * some fraction of a page if allocations cannot be satisfied due to
- * size constraints on boxes where there is physical RAM space
- * fragmentation - in these cases (mostly large memory boxes) this
- * is not a problem.
- *
- * On low memory boxes we get it right in 100% of the cases.
- *
- * alignment has to be a power of 2 value.
- *
- * NOTE: This function is _not_ reentrant.
- */
-static void * __init
-alloc_bootmem_core(struct bootmem_data *bdata, unsigned long size,
- unsigned long align, unsigned long goal, unsigned long limit)
+static void * __init alloc_bootmem_core(struct bootmem_data *bdata,
+ unsigned long size, unsigned long align,
+ unsigned long goal, unsigned long limit)
{
- unsigned long areasize, preferred;
- unsigned long i, start = 0, incr, eidx, end_pfn;
- void *ret;
- unsigned long node_boot_start;
- void *node_bootmem_map;
+ unsigned long min, max, start, sidx, midx, step;
- if (!size) {
- printk("alloc_bootmem_core(): zero-sized request\n");
- BUG();
- }
- BUG_ON(align & (align-1));
+ BUG_ON(!size);
+ BUG_ON(align & (align - 1));
+ BUG_ON(limit && goal + size > limit);
- /* on nodes without memory - bootmem_map is NULL */
if (!bdata->node_bootmem_map)
return NULL;
@@ -468,126 +449,85 @@
bdata - bootmem_node_data, size, PAGE_ALIGN(size) >> PAGE_SHIFT,
align, goal, limit);
- /* bdata->node_boot_start is supposed to be (12+6)bits alignment on x86_64 ? */
- node_boot_start = bdata->node_boot_start;
- node_bootmem_map = bdata->node_bootmem_map;
- if (align) {
- node_boot_start = ALIGN(bdata->node_boot_start, align);
- if (node_boot_start > bdata->node_boot_start)
- node_bootmem_map = (unsigned long *)bdata->node_bootmem_map +
- PFN_DOWN(node_boot_start - bdata->node_boot_start)/BITS_PER_LONG;
- }
+ min = PFN_DOWN(bdata->node_boot_start);
+ max = bdata->node_low_pfn;
- if (limit && node_boot_start >= limit)
+ goal >>= PAGE_SHIFT;
+ limit >>= PAGE_SHIFT;
+
+ if (limit && max > limit)
+ max = limit;
+ if (max <= min)
return NULL;
- end_pfn = bdata->node_low_pfn;
- limit = PFN_DOWN(limit);
- if (limit && end_pfn > limit)
- end_pfn = limit;
+ step = max(align >> PAGE_SHIFT, 1UL);
- eidx = end_pfn - PFN_DOWN(node_boot_start);
+ if (goal && min < goal && goal < max)
+ start = ALIGN(goal, step);
+ else
+ start = ALIGN(min, step);
- /*
- * We try to allocate bootmem pages above 'goal'
- * first, then we try to allocate lower pages.
- */
- preferred = 0;
- if (goal && PFN_DOWN(goal) < end_pfn) {
- if (goal > node_boot_start)
- preferred = goal - node_boot_start;
+ sidx = start - PFN_DOWN(bdata->node_boot_start);
+ midx = max - PFN_DOWN(bdata->node_boot_start);
- if (bdata->last_success > node_boot_start &&
- bdata->last_success - node_boot_start >= preferred)
- if (!limit || (limit && limit > bdata->last_success))
- preferred = bdata->last_success - node_boot_start;
+ if (bdata->hint_idx > sidx) {
+ /* Make sure we retry on failure */
+ goal = 1;
+ sidx = ALIGN(bdata->hint_idx, step);
}
- preferred = PFN_DOWN(ALIGN(preferred, align));
- areasize = (size + PAGE_SIZE-1) / PAGE_SIZE;
- incr = align >> PAGE_SHIFT ? : 1;
+ while (1) {
+ int merge;
+ void *region;
+ unsigned long eidx, i, start_off, end_off;
+find_block:
+ sidx = find_next_zero_bit(bdata->node_bootmem_map, midx, sidx);
+ sidx = ALIGN(sidx, step);
+ eidx = sidx + PFN_UP(size);
-restart_scan:
- for (i = preferred; i < eidx;) {
- unsigned long j;
-
- i = find_next_zero_bit(node_bootmem_map, eidx, i);
- i = ALIGN(i, incr);
- if (i >= eidx)
+ if (sidx >= midx || eidx > midx)
break;
- if (test_bit(i, node_bootmem_map)) {
- i += incr;
- continue;
- }
- for (j = i + 1; j < i + areasize; ++j) {
- if (j >= eidx)
- goto fail_block;
- if (test_bit(j, node_bootmem_map))
- goto fail_block;
- }
- start = i;
- goto found;
- fail_block:
- i = ALIGN(j, incr);
- if (i == j)
- i += incr;
+
+ for (i = sidx; i < eidx; i++)
+ if (test_bit(i, bdata->node_bootmem_map)) {
+ sidx = ALIGN(i, step);
+ if (sidx == i)
+ sidx += step;
+ goto find_block;
+ }
+
+ if (bdata->last_end_off &&
+ PFN_DOWN(bdata->last_end_off) + 1 == sidx)
+ start_off = ALIGN(bdata->last_end_off, align);
+ else
+ start_off = PFN_PHYS(sidx);
+
+ merge = PFN_DOWN(start_off) < sidx;
+ end_off = start_off + size;
+
+ bdata->last_end_off = end_off;
+ bdata->hint_idx = PFN_UP(end_off);
+
+ /*
+ * Reserve the area now:
+ */
+ for (i = PFN_DOWN(start_off) + merge;
+ i < PFN_UP(end_off); i++)
+ if (test_and_set_bit(i, bdata->node_bootmem_map))
+ BUG();
+
+ region = phys_to_virt(bdata->node_boot_start + start_off);
+ memset(region, 0, size);
+ return region;
}
- if (preferred > 0) {
- preferred = 0;
- goto restart_scan;
+ if (goal) {
+ goal = 0;
+ sidx = 0;
+ goto find_block;
}
+
return NULL;
-
-found:
- bdata->last_success = PFN_PHYS(start) + node_boot_start;
- BUG_ON(start >= eidx);
-
- /*
- * Is the next page of the previous allocation-end the start
- * of this allocation's buffer? If yes then we can 'merge'
- * the previous partial page with this allocation.
- */
- if (align < PAGE_SIZE &&
- bdata->last_offset && bdata->last_pos+1 == start) {
- unsigned long offset, remaining_size;
- offset = ALIGN(bdata->last_offset, align);
- BUG_ON(offset > PAGE_SIZE);
- remaining_size = PAGE_SIZE - offset;
- if (size < remaining_size) {
- areasize = 0;
- /* last_pos unchanged */
- bdata->last_offset = offset + size;
- ret = phys_to_virt(bdata->last_pos * PAGE_SIZE +
- offset + node_boot_start);
- } else {
- remaining_size = size - remaining_size;
- areasize = (remaining_size + PAGE_SIZE-1) / PAGE_SIZE;
- ret = phys_to_virt(bdata->last_pos * PAGE_SIZE +
- offset + node_boot_start);
- bdata->last_pos = start + areasize - 1;
- bdata->last_offset = remaining_size;
- }
- bdata->last_offset &= ~PAGE_MASK;
- } else {
- bdata->last_pos = start + areasize - 1;
- bdata->last_offset = size & ~PAGE_MASK;
- ret = phys_to_virt(start * PAGE_SIZE + node_boot_start);
- }
-
- bdebug("nid=%td start=%lx end=%lx\n",
- bdata - bootmem_node_data,
- start + PFN_DOWN(bdata->node_boot_start),
- start + areasize + PFN_DOWN(bdata->node_boot_start));
-
- /*
- * Reserve the area now:
- */
- for (i = start; i < start + areasize; i++)
- if (unlikely(test_and_set_bit(i, node_bootmem_map)))
- BUG();
- memset(ret, 0, size);
- return ret;
}
/**