From: Milan Broz <mbroz@redhat.com>
Date: Thu, 24 Apr 2008 20:42:36 +0000 (+0100)
Subject: dm snapshot: reduce default memory allocation
X-Git-Tag: v2.6.26-rc1~1064^2~22
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=8ee2767a5903fde549fd3597690f64c8d951051a;p=linux-2.6-omap-h63xx.git

dm snapshot: reduce default memory allocation

Limit the amount of memory allocated per snapshot on systems
with a large page size.  (The larger default chunk size on
these systems compensates for the smaller number of pages reserved.)

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
---

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 4dc8a43c034..08047fb1cac 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -36,9 +36,9 @@
 #define SNAPSHOT_COPY_PRIORITY 2
 
 /*
- * Each snapshot reserves this many pages for io
+ * Reserve 1MB for each snapshot initially (with minimum of 1 page).
  */
-#define SNAPSHOT_PAGES 256
+#define SNAPSHOT_PAGES (((1UL << 20) >> PAGE_SHIFT) ? : 1)
 
 static struct workqueue_struct *ksnapd;
 static void flush_queued_bios(struct work_struct *work);