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authorTao Ma <tao.ma@oracle.com>2009-02-25 00:53:23 +0800
committerMark Fasheh <mfasheh@suse.com>2009-04-03 11:39:17 -0700
commit138211515c102807a16c02fdc15feef1f6ef8124 (patch)
tree9b6fff8512a19792f2e29458292607f4efb413c4 /fs/ocfs2/suballoc.c
parent1d46dc08d33138c29c63d717807c08ab704fc773 (diff)
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ocfs2: Optimize inode allocation by remembering last group
In ocfs2, the inode block search looks for the "emptiest" inode group to allocate from. So if an inode alloc file has many equally (or almost equally) empty groups, new inodes will tend to get spread out amongst them, which in turn can put them all over the disk. This is undesirable because directory operations on conceptually "nearby" inodes force a large number of seeks. So we add ip_last_used_group in core directory inodes which records the last used allocation group. Another field named ip_last_used_slot is also added in case inode stealing happens. When claiming new inode, we passed in directory's inode so that the allocation can use this information. For more details, please see http://oss.oracle.com/osswiki/OCFS2/DesignDocs/InodeAllocationStrategy. Signed-off-by: Tao Ma <tao.ma@oracle.com> Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Diffstat (limited to 'fs/ocfs2/suballoc.c')
-rw-r--r--fs/ocfs2/suballoc.c36
1 files changed, 36 insertions, 0 deletions
diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
index a69628603e1..487f00c45f8 100644
--- a/fs/ocfs2/suballoc.c
+++ b/fs/ocfs2/suballoc.c
@@ -1618,8 +1618,41 @@ bail:
return status;
}
+static void ocfs2_init_inode_ac_group(struct inode *dir,
+ struct buffer_head *parent_fe_bh,
+ struct ocfs2_alloc_context *ac)
+{
+ struct ocfs2_dinode *fe = (struct ocfs2_dinode *)parent_fe_bh->b_data;
+ /*
+ * Try to allocate inodes from some specific group.
+ *
+ * If the parent dir has recorded the last group used in allocation,
+ * cool, use it. Otherwise if we try to allocate new inode from the
+ * same slot the parent dir belongs to, use the same chunk.
+ *
+ * We are very careful here to avoid the mistake of setting
+ * ac_last_group to a group descriptor from a different (unlocked) slot.
+ */
+ if (OCFS2_I(dir)->ip_last_used_group &&
+ OCFS2_I(dir)->ip_last_used_slot == ac->ac_alloc_slot)
+ ac->ac_last_group = OCFS2_I(dir)->ip_last_used_group;
+ else if (le16_to_cpu(fe->i_suballoc_slot) == ac->ac_alloc_slot)
+ ac->ac_last_group = ocfs2_which_suballoc_group(
+ le64_to_cpu(fe->i_blkno),
+ le16_to_cpu(fe->i_suballoc_bit));
+}
+
+static inline void ocfs2_save_inode_ac_group(struct inode *dir,
+ struct ocfs2_alloc_context *ac)
+{
+ OCFS2_I(dir)->ip_last_used_group = ac->ac_last_group;
+ OCFS2_I(dir)->ip_last_used_slot = ac->ac_alloc_slot;
+}
+
int ocfs2_claim_new_inode(struct ocfs2_super *osb,
handle_t *handle,
+ struct inode *dir,
+ struct buffer_head *parent_fe_bh,
struct ocfs2_alloc_context *ac,
u16 *suballoc_bit,
u64 *fe_blkno)
@@ -1635,6 +1668,8 @@ int ocfs2_claim_new_inode(struct ocfs2_super *osb,
BUG_ON(ac->ac_bits_wanted != 1);
BUG_ON(ac->ac_which != OCFS2_AC_USE_INODE);
+ ocfs2_init_inode_ac_group(dir, parent_fe_bh, ac);
+
status = ocfs2_claim_suballoc_bits(osb,
ac,
handle,
@@ -1653,6 +1688,7 @@ int ocfs2_claim_new_inode(struct ocfs2_super *osb,
*fe_blkno = bg_blkno + (u64) (*suballoc_bit);
ac->ac_bits_given++;
+ ocfs2_save_inode_ac_group(dir, ac);
status = 0;
bail:
mlog_exit(status);