[patch 4/12] tunable ext3 commit interval

Andrew Morton (akpm@zip.com.au)
Fri, 09 Aug 2002 17:56:47 -0700


The patch from Stephen Tweedie allows users to modify the journal
commit interval for the ext3 filesystem.

The commit interval is normally five seconds. For portable computers
with spun-down drives it is advantageous to be able to increase the
commit interval.

There may also be advantages in decreasing the commit interval for
specialised applications such as heavily-loaded NFS servers which are
using synchronous exports.

The laptop users will also need to increase the pdflush periodic
writeback interval (/proc/sys/vm/dirty_writeback_centisecs), because
the `kupdate' activity also forces a commit.

To specify the commit interval, use

mount -o commit=30 /dev/hda1 /mnt/whatever

or
mount -o remount,commit=30 /dev/hda1

The commit interval is specified in units of seconds.

super.c | 26 +++++++++++++++++++++++++-
1 files changed, 25 insertions, 1 deletion

--- 2.5.30/fs/ext3/super.c~ext3-commit-interval Fri Aug 9 17:36:40 2002
+++ 2.5.30-akpm/fs/ext3/super.c Fri Aug 9 17:36:41 2002
@@ -696,6 +696,11 @@ static int parse_options (char * options
*mount_options &= ~EXT3_MOUNT_DATA_FLAGS;
*mount_options |= data_opt;
}
+ } else if (!strcmp (this_char, "commit")) {
+ unsigned long v;
+ if (want_numeric(value, "commit", &v))
+ return 0;
+ sbi->s_commit_interval = (HZ * v);
} else {
printk (KERN_ERR
"EXT3-fs: Unrecognized mount option %s\n",
@@ -1260,6 +1265,22 @@ out_fail:
return -EINVAL;
}

+/*
+ * Setup any per-fs journal parameters now. We'll do this both on
+ * initial mount, once the journal has been initialised but before we've
+ * done any recovery; and again on any subsequent remount.
+ */
+static void ext3_init_journal_params(struct ext3_sb_info *sbi,
+ journal_t *journal)
+{
+ if (sbi->s_commit_interval)
+ journal->j_commit_interval = sbi->s_commit_interval;
+ /* We could also set up an ext3-specific default for the commit
+ * interval here, but for now we'll just fall back to the jbd
+ * default. */
+}
+
+
static journal_t *ext3_get_journal(struct super_block *sb, int journal_inum)
{
struct inode *journal_inode;
@@ -1294,7 +1315,7 @@ static journal_t *ext3_get_journal(struc
printk(KERN_ERR "EXT3-fs: Could not load journal inode\n");
iput(journal_inode);
}
-
+ ext3_init_journal_params(EXT3_SB(sb), journal);
return journal;
}

@@ -1371,6 +1392,7 @@ static journal_t *ext3_get_dev_journal(s
goto out_journal;
}
EXT3_SB(sb)->journal_bdev = bdev;
+ ext3_init_journal_params(EXT3_SB(sb), journal);
return journal;
out_journal:
journal_destroy(journal);
@@ -1667,6 +1689,8 @@ int ext3_remount (struct super_block * s

es = sbi->s_es;

+ ext3_init_journal_params(sbi, sbi->s_journal);
+
if ((*flags & MS_RDONLY) != (sb->s_flags & MS_RDONLY)) {
if (sbi->s_mount_opt & EXT3_MOUNT_ABORT)
return -EROFS;

.
-
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