From: Evgeniy Ivanov <lolkaantimat@gmail.com>
Date: Thu, 11 Aug 2011 15:12:07 +0000 (+0400)
Subject: MFS: optimize dentry acllocation.
X-Git-Tag: v3.2.0~358
X-Git-Url: http://zhaoyanbai.com/repos/%22http:/www.isc.org/icons/doxygen.png?a=commitdiff_plain;h=bc434254ea5f25ce6cadaa81c722995c199f510d;p=minix.git

MFS: optimize dentry acllocation.

When search for free slot always cache position of last allocated slot,
so next time when need to allocate new slot, we can search from that
position.
---

diff --git a/servers/mfs/inode.c b/servers/mfs/inode.c
index 31a2777cc..210ea844e 100644
--- a/servers/mfs/inode.c
+++ b/servers/mfs/inode.c
@@ -172,6 +172,7 @@ PUBLIC struct inode *get_inode(
   rip->i_update = 0;		/* all the times are initially up-to-date */
   rip->i_zsearch = NO_ZONE;	/* no zones searched for yet */
   rip->i_mountpoint= FALSE;
+  rip->i_last_dpos = 0;		/* no dentries searched for yet */
 
   /* Add to hash */
   addhash_inode(rip);
diff --git a/servers/mfs/inode.h b/servers/mfs/inode.h
index c3ddbbd75..f66532c3a 100644
--- a/servers/mfs/inode.h
+++ b/servers/mfs/inode.h
@@ -36,6 +36,7 @@ EXTERN struct inode {
   struct super_block *i_sp;	/* pointer to super block for inode's device */
   char i_dirt;			/* CLEAN or DIRTY */
   zone_t i_zsearch;		/* where to start search for new zones */
+  off_t i_last_dpos;		/* where to start dentry search */
   
   char i_mountpoint;		/* true if mounted on */
 
diff --git a/servers/mfs/path.c b/servers/mfs/path.c
index 8d32dd641..3a3f42e33 100644
--- a/servers/mfs/path.c
+++ b/servers/mfs/path.c
@@ -519,7 +519,13 @@ int check_permissions;		 /* check permissions when flag is !IS_EMPTY */
   e_hit = FALSE;
   match = 0;			/* set when a string match occurs */
 
-  for (pos = 0; pos < ldir_ptr->i_size; pos += ldir_ptr->i_sp->s_block_size) {
+  pos = 0;
+  if (flag == ENTER && ldir_ptr->i_last_dpos < ldir_ptr->i_size) {
+	pos = ldir_ptr->i_last_dpos;
+	new_slots = (unsigned) (pos/DIR_ENTRY_SIZE);
+  }
+
+  for (; pos < ldir_ptr->i_size; pos += ldir_ptr->i_sp->s_block_size) {
 	b = read_map(ldir_ptr, pos);	/* get block number */
 
 	/* Since directories don't have holes, 'b' cannot be NO_BLOCK. */
@@ -561,6 +567,8 @@ int check_permissions;		 /* check permissions when flag is !IS_EMPTY */
 				bp->b_dirt = DIRTY;
 				ldir_ptr->i_update |= CTIME | MTIME;
 				ldir_ptr->i_dirt = DIRTY;
+				if (pos < ldir_ptr->i_last_dpos)
+					ldir_ptr->i_last_dpos = pos;
 			} else {
 				sp = ldir_ptr->i_sp;	/* 'flag' is LOOK_UP */
 				*numb = (ino_t) conv4(sp->s_native,
@@ -587,6 +595,11 @@ int check_permissions;		 /* check permissions when flag is !IS_EMPTY */
   	return(flag == IS_EMPTY ? OK : ENOENT);
   }
 
+  /* When ENTER next time, start searching for free slot from
+   * i_last_dpos. It gives some performance improvement (3-5%).
+   */
+  ldir_ptr->i_last_dpos = pos;
+
   /* This call is for ENTER.  If no free slot has been found so far, try to
    * extend directory.
    */