linux-ext4 - [PATCH] EXT4: optimizing group serch for inode allocation

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Date:	Sat, 19 Dec 2015 05:02:56 +0530
From:	lokesh jaliminche <lokesh.jaliminche@...il.com>
To:	Andreas Dilger <adilger@...ger.ca>
Cc:	linux-ext4@...r.kernel.org
Subject: [PATCH] EXT4: optimizing group serch for inode allocation

>From 9e09fef78b2fa552c883bf8124af873abfde0805 Mon Sep 17 00:00:00 2001
From: Lokesh Nagappa Jaliminche <lokesh.jaliminche@...gate.com>

Added a check at the start of group search loop to
avoid looping unecessarily in case of empty group.
This also allow group search to jump directly to
"found_flex_bg" with "stats" and "group" already set,
so there is no need to go through the extra steps of
setting "best_desc" and "best_group" and then break
out of the loop just to set "stats" and "group" again.

Signed-off-by: Lokesh N Jaliminche <lokesh.jaliminche@...il.com>
---
 fs/ext4/ialloc.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 1b8024d..588bf8e 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -446,6 +446,8 @@ static int find_group_orlov(struct super_block
*sb, struct inode *parent,
  struct ext4_sb_info *sbi = EXT4_SB(sb);
  ext4_group_t real_ngroups = ext4_get_groups_count(sb);
  int inodes_per_group = EXT4_INODES_PER_GROUP(sb);
+ unsigned int inodes_per_flex_group;
+ long unsigned int blocks_per_clustre;
  unsigned int freei, avefreei, grp_free;
  ext4_fsblk_t freeb, avefreec;
  unsigned int ndirs;
@@ -470,6 +472,8 @@ static int find_group_orlov(struct super_block
*sb, struct inode *parent,
  percpu_counter_read_positive(&sbi->s_freeclusters_counter));
  avefreec = freeb;
  do_div(avefreec, ngroups);
+ inodes_per_flex_group = inodes_per_group * flex_size;
+ blocks_per_clustre = sbi->s_blocks_per_group * flex_size;
  ndirs = percpu_counter_read_positive(&sbi->s_dirs_counter);

  if (S_ISDIR(mode) &&
@@ -489,6 +493,10 @@ static int find_group_orlov(struct super_block
*sb, struct inode *parent,
  for (i = 0; i < ngroups; i++) {
  g = (parent_group + i) % ngroups;
  get_orlov_stats(sb, g, flex_size, &stats);
+ /* the group can't get any better than empty */
+ if (inodes_per_flex_group == stats.free_inodes &&
+ blocks_per_clustre == stats.free_clusters)
+ goto found_flex_bg;
  if (!stats.free_inodes)
  continue;
  if (stats.used_dirs >= best_ndir)
-- 
1.7.1

Download attachment "0001-EXT4-optimizing-group-serch-for-inode-allocation.patch" of type "application/octet-stream" (2208 bytes)