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Subject[RFC][PATCH] dump fragmentation stats for buddy allocator
This small patch creates /proc/buddyinfo, which
shows how many of each order page groups are available.
It has *not* been well tested.

Thanks to wli for pointing out that infinite loops whilst
holding vm locks with interrupts disbabled are probably
not a Good Thing (tm).

Comments / abuse / testing all welcome.

M.

--- virgin-2.4.19-pre8/fs/proc/proc_misc.c Tue May 7 15:21:57 2002
+++ linux-2.4.19-pre8-buddystats/fs/proc/proc_misc.c Tue May 21 20:02:18 2002
@@ -193,6 +193,21 @@
#undef K
}

+extern int buddyinfo(char *buf, int node_id);
+
+int buddyinfo_read_proc(char *page, char **start, off_t off,
+ int count, int *eof, void *data)
+{
+ int node_id;
+ int len = 0;
+
+ for (node_id = 0; node_id < numnodes; node_id++) {
+ len += buddyinfo(page+len, node_id);
+ }
+
+ return proc_calc_metrics(page, start, off, count, eof, len);
+}
+
static int version_read_proc(char *page, char **start, off_t off,
int count, int *eof, void *data)
{
@@ -580,4 +595,7 @@
slabinfo_read_proc, NULL);
if (entry)
entry->write_proc = slabinfo_write_proc;
+
+ create_proc_read_entry("buddyinfo", S_IWUSR | S_IRUGO, NULL,
+ buddyinfo_read_proc, NULL);
}
--- virgin-2.4.19-pre8/mm/page_alloc.c Tue May 7 15:22:12 2002
+++ linux-2.4.19-pre8-buddystats/mm/page_alloc.c Wed May 22 01:07:53 2002
@@ -877,3 +877,39 @@
}

__setup("memfrac=", setup_mem_frac);
+
+
+/*
+ * This walks the freelist for each zone. Whilst this is slow, I'd rather
+ * be slow here than slow down the fast path by keeping stats - mjbligh
+ */
+int buddyinfo(char *buf, int node_id)
+{
+ int zone_id, order, free, len = 0;
+ unsigned long flags;
+ zone_t *zone;
+ free_area_t * area;
+ struct list_head *head, *curr;
+
+ for (zone_id = 0; zone_id < MAX_NR_ZONES; ++zone_id) {
+ zone = &(NODE_DATA(node_id)->node_zones[zone_id]);
+ if (zone->size == 0)
+ continue;
+ spin_lock_irqsave(&zone->lock, flags);
+ len += sprintf(buf+len, "Node %d, Zone %8s, ",
+ node_id, zone->name);
+ for (order = 0; order < MAX_ORDER; ++order) {
+ area = zone->free_area + order;
+ head = &area->free_list;
+ free = 0;
+ for (curr = memlist_next(head); curr != head; curr = memlist_next(curr))
+ ++free;
+ len += sprintf(buf+len, "%d ", free);
+ }
+ len += sprintf(buf+len, "\n");
+ spin_unlock_irqrestore(&zone->lock, flags);
+ }
+
+ return len;
+}
+
-
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