linux-kernel - [PATCH 20/25] lmb: Add arch function to control coalescing of lmb memory regions

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Date:	Mon, 10 May 2010 19:38:54 +1000
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	linux-mm@...ck.org
Cc:	linux-kernel@...r.kernel.org, tglx@...uxtronix.de, mingo@...e.hu,
	davem@...emloft.net, lethal@...ux-sh.org,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Subject: [PATCH 20/25] lmb: Add arch function to control coalescing of lmb memory regions

Some archs such as ARM want to avoid coalescing accross things such
as the lowmem/highmem boundary or similar. This provides the option
to control it via an arch callback for which a weak default is provided
which always allows coalescing.

Signed-off-by: Benjamin Herrenschmidt <benh@...nel.crashing.org>
---
 include/linux/lmb.h |    2 ++
 lib/lmb.c           |   19 ++++++++++++++++++-
 2 files changed, 20 insertions(+), 1 deletions(-)

diff --git a/include/linux/lmb.h b/include/linux/lmb.h
index e575801..404b49c 100644
--- a/include/linux/lmb.h
+++ b/include/linux/lmb.h
@@ -70,6 +70,8 @@ extern void lmb_dump_all(void);
 
 /* Provided by the architecture */
 extern phys_addr_t lmb_nid_range(phys_addr_t start, phys_addr_t end, int *nid);
+extern int lmb_memory_can_coalesce(phys_addr_t addr1, phys_addr_t size1,
+				   phys_addr_t addr2, phys_addr_t size2);
 
 /**
  * lmb_set_current_limit - Set the current allocation limit to allow
diff --git a/lib/lmb.c b/lib/lmb.c
index 2602683..84ac3a9 100644
--- a/lib/lmb.c
+++ b/lib/lmb.c
@@ -235,6 +235,12 @@ static int lmb_double_array(struct lmb_type *type)
 	return 0;
 }
 
+extern int __weak lmb_memory_can_coalesce(phys_addr_t addr1, phys_addr_t size1,
+					  phys_addr_t addr2, phys_addr_t size2)
+{
+	return 1;
+}
+
 static long lmb_add_region(struct lmb_type *type, phys_addr_t base, phys_addr_t size)
 {
 	unsigned long coalesced = 0;
@@ -256,6 +262,10 @@ static long lmb_add_region(struct lmb_type *type, phys_addr_t base, phys_addr_t
 			return 0;
 
 		adjacent = lmb_addrs_adjacent(base, size, rgnbase, rgnsize);
+		/* Check if arch allows coalescing */
+		if (adjacent != 0 && type == &lmb.memory &&
+		    !lmb_memory_can_coalesce(base, size, rgnbase, rgnsize))
+			break;
 		if (adjacent > 0) {
 			type->regions[i].base -= size;
 			type->regions[i].size += size;
@@ -268,7 +278,14 @@ static long lmb_add_region(struct lmb_type *type, phys_addr_t base, phys_addr_t
 		}
 	}
 
-	if ((i < type->cnt - 1) && lmb_regions_adjacent(type, i, i+1)) {
+	/* If we plugged a hole, we may want to also coalesce with the
+	 * next region
+	 */
+	if ((i < type->cnt - 1) && lmb_regions_adjacent(type, i, i+1) &&
+	    ((type != &lmb.memory || lmb_memory_can_coalesce(type->regions[i].base,
+							     type->regions[i].size,
+							     type->regions[i+1].base,
+							     type->regions[i+1].size)))) {
 		lmb_coalesce_regions(type, i, i+1);
 		coalesced++;
 	}
-- 
1.6.3.3

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