In e2fsck_pass4(), we were consulting inode_dir_map using
ext2fs_test_inode_bitmap2() for every single inode in the file system.
However, there were many cases where we never needed the result of the
test --- most notably if the inode is not in use.
I was a bit surprised that GCC 4.7 with CFLAGS set to "-g -O2" wasn't
able to optimize this out for us, but here is the pass 4 timing for an
empty 3T file system before this patch:
Pass 4: Memory used: 672k/772k (422k/251k), time: 3.67/ 3.66/ 0.00
and afterwards, we see a 43% improvement:
Pass 4: Memory used: 672k/772k (422k/251k), time: 2.09/ 2.08/ 0.00
Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
---
e2fsck/pass4.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/e2fsck/pass4.c b/e2fsck/pass4.c
index 1e63280..2d55180 100644
--- a/e2fsck/pass4.c
+++ b/e2fsck/pass4.c
@@ -123,7 +123,7 @@ void e2fsck_pass4(e2fsck_t ctx)
/* Protect loop from wrap-around if s_inodes_count maxed */
for (i=1; i <= fs->super->s_inodes_count && i > 0; i++) {
- int isdir = ext2fs_test_inode_bitmap2(ctx->inode_dir_map, i);
+ int isdir;
if (ctx->flags & E2F_FLAG_SIGNAL_MASK)
goto errout;
@@ -157,6 +157,7 @@ void e2fsck_pass4(e2fsck_t ctx)
ext2fs_icount_fetch(ctx->inode_count, i,
&link_counted);
}
+ isdir = ext2fs_test_inode_bitmap2(ctx->inode_dir_map, i);
if (isdir && (link_counted > EXT2_LINK_MAX))
link_counted = 1;
if (link_counted != link_count) {
--
1.7.12.rc0.22.gcdd159b
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
