JFS: performance patch

Basically, we saw a large amount of time spent in the
jfs_strfromUCS_le() function, mispredicting the branch inside the
loop, so I just added some unlikely modifiers to the if statements to
re-ordered the code.  Again, these simple changes provided > 2 % on
spec-sfs, so please consider it for inclusion.

Signed-off-by: Dave Kleikamp <shaggy@austin.ibm.com>

diff --git a/fs/jfs/jfs_unicode.c b/fs/jfs/jfs_unicode.c
index b32208a..f327dec 100644 (file)
--- a/fs/jfs/jfs_unicode.c
+++ b/fs/jfs/jfs_unicode.c
@@ -51,8 +51,9 @@ int jfs_strfromUCS_le(char *to, const __le16 * from,
                }
        } else {
                for (i = 0; (i < len) && from[i]; i++) {
-                       if (le16_to_cpu(from[i]) & 0xff00) {
-                               if (warn) {
+                       if (unlikely(le16_to_cpu(from[i]) & 0xff00)) {
+                               to[i] = '?';
+                               if (unlikely(warn)) {
                                        warn--;
                                        warn_again--;
                                        printk(KERN_ERR
@@ -61,7 +62,7 @@ int jfs_strfromUCS_le(char *to, const __le16 * from,
                                        printk(KERN_ERR
                                "mount with iocharset=utf8 to access\n");
                                }
-                               to[i] = '?';
+
                        }
                        else
                                to[i] = (char) (le16_to_cpu(from[i]));