From: Bob Peterson <rpeterso@redhat.com>
To: cluster-devel.redhat.com
Subject: [Cluster-devel] [PATCH 1/5] GFS2: optimize rbm_from_block wrt bi_start
Date: Wed, 11 Sep 2013 13:43:56 -0500 [thread overview]
Message-ID: <1378925045-23318-2-git-send-email-rpeterso@redhat.com> (raw)
In function gfs2_rbm_from_block, it starts by checking if the block
falls within the first bitmap. It does so by checking if the rbm's
offset is less than (rbm->bi->bi_start + rbm->bi->bi_len) * GFS2_NBBY.
However, the first bitmap will always have bi_start==0. Therefore
this is an unnecessary calculation in a function that gets called
billions of times. This patch removes the reference to bi_start.
---
fs/gfs2/rgrp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 6931743..7a6fa03 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -262,7 +262,7 @@ static int gfs2_rbm_from_block(struct gfs2_rbm *rbm, u64 block)
rbm->bi = rbm->rgd->rd_bits;
rbm->offset = (u32)(rblock);
/* Check if the block is within the first block */
- if (rbm->offset < (rbm->bi->bi_start + rbm->bi->bi_len) * GFS2_NBBY)
+ if (rbm->offset < rbm->bi->bi_len * GFS2_NBBY)
return 0;
/* Adjust for the size diff between gfs2_meta_header and gfs2_rgrp */
--
1.8.3.1
reply other threads:[~2013-09-11 18:43 UTC|newest]
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