From: Theodore Ts'o <tytso@mit.edu>
To: linux-ext4@vger.kernel.org
Cc: Theodore Ts'o <tytso@mit.edu>
Subject: [PATCH, RFC 11/12] ext4: tune mballoc's default group prealloc size for bigalloc file systems
Date: Sat, 19 Mar 2011 17:28:36 -0400 [thread overview]
Message-ID: <1300570117-24048-12-git-send-email-tytso@mit.edu> (raw)
In-Reply-To: <1300570117-24048-1-git-send-email-tytso@mit.edu>
The default group preallocation size had been previously set to 512
blocks/clusters, regardless of the block/cluster size. This is
probably too big for large cluster sizes. So adjust the default so
that it is 2 megabytes or 32 clusters, whichever is larger.
---
fs/ext4/mballoc.c | 15 ++++++++++++++-
1 files changed, 14 insertions(+), 1 deletions(-)
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 02f099f..ad4a6eb 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2529,7 +2529,20 @@ int ext4_mb_init(struct super_block *sb, int needs_recovery)
sbi->s_mb_stats = MB_DEFAULT_STATS;
sbi->s_mb_stream_request = MB_DEFAULT_STREAM_THRESHOLD;
sbi->s_mb_order2_reqs = MB_DEFAULT_ORDER2_REQS;
- sbi->s_mb_group_prealloc = MB_DEFAULT_GROUP_PREALLOC;
+ /*
+ * The default group preallocation is 512, which for 4k block
+ * sizes translates to 2 megabytes. However for bigalloc file
+ * systems, this is probably too big (i.e, if the cluster size
+ * is 1 megabyte, then group preallocation size becomes half a
+ * gigabyte!). As a default, we will keep a two megabyte
+ * group pralloc size for cluster sizes up to 64k, and after
+ * that, we will force a minimum group preallocation size of
+ * 32 clusters. This translates to 8 megs when the cluster
+ * size is 256k, and 32 megs when the cluster size is 1 meg,
+ * which seems reasonable as a default.
+ */
+ sbi->s_mb_group_prealloc = max(MB_DEFAULT_GROUP_PREALLOC >>
+ sbi->s_cluster_bits, 32);
sbi->s_locality_groups = alloc_percpu(struct ext4_locality_group);
if (sbi->s_locality_groups == NULL) {
--
1.7.3.1
next prev parent reply other threads:[~2011-03-19 21:37 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-19 21:28 [PATCH, RFC 00/12] bigalloc patchset Theodore Ts'o
2011-03-19 21:28 ` [PATCH, RFC 01/12] ext4: read-only support for bigalloc file systems Theodore Ts'o
2011-03-21 19:35 ` Lukas Czerner
2011-03-22 17:02 ` Ted Ts'o
2011-03-23 10:28 ` Lukas Czerner
2011-03-19 21:28 ` [PATCH, RFC 02/12] ext4: enforce bigalloc restrictions (e.g., no online resizing, etc.) Theodore Ts'o
2011-03-19 21:28 ` [PATCH, RFC 03/12] ext4: Convert instances of EXT4_BLOCKS_PER_GROUP to EXT4_CLUSTERS_PER_GROUP Theodore Ts'o
2011-03-20 10:26 ` Amir Goldstein
2011-03-21 13:12 ` Ted Ts'o
2011-03-19 21:28 ` [PATCH, RFC 04/12] ext4: Remove block bitmap initialization in ext4_new_inode() Theodore Ts'o
2011-03-19 21:28 ` [PATCH, RFC 05/12] ext4: factor out block group accounting into functions Theodore Ts'o
2011-03-19 21:28 ` [PATCH, RFC 06/12] ext4: split out ext4_free_blocks_after_init() Theodore Ts'o
2011-03-19 21:28 ` [PATCH, RFC 07/12] ext4: bigalloc changes to block bitmap initialization functions Theodore Ts'o
2011-03-19 21:28 ` [PATCH, RFC 08/12] ext4: Convert block group-relative offsets to use clusters Theodore Ts'o
2011-03-19 21:28 ` [PATCH, RFC 09/12] ext4: teach ext4_ext_map_blocks() about the bigalloc feature Theodore Ts'o
2011-03-19 21:28 ` [PATCH, RFC 10/12] ext4: teach ext4_statfs() to deal with clusters if bigalloc is enabled Theodore Ts'o
2011-03-21 20:17 ` Lukas Czerner
2011-03-22 22:09 ` Ted Ts'o
2011-03-19 21:28 ` Theodore Ts'o [this message]
2011-03-19 21:28 ` [PATCH, RFC 12/12] ext4: enable mounting bigalloc as read/write Theodore Ts'o
2011-03-20 10:33 ` [PATCH, RFC 00/12] bigalloc patchset Amir Goldstein
2011-03-21 8:55 ` Andreas Dilger
2011-03-21 11:31 ` Rogier Wolff
2011-03-21 13:24 ` Ted Ts'o
2011-03-21 23:42 ` Andreas Dilger
2011-04-05 17:23 ` Coly Li
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