[PATCH 2/3] writeback: introduce dirty_volatile_interval

[Fengguang Wu <wfg@mail.ustc.edu.cn>]

Introduce dirty_volatile_interval for the minimal dirty time.
Inodes dirtied less than dirty_volatile_interval will not be
considered for syncing by kupdate-style writeback.

This new parameter will be used in clustered writeback.
The old dirty_expire_interval is still(but less) respected.

Cc: Chris Mason <chris.mason@oracle.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: David Chinner <dgc@sgi.com>
Cc: Ken Chen <kenchen@google.com>
Cc: Michael Rubin <mrubin@google.com>
Cc: Andrew Morton <akpm@osdl.org>
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
---
 include/linux/writeback.h |    1 +
 kernel/sysctl.c           |    7 +++++++
 mm/page-writeback.c       |    5 +++++
 3 files changed, 13 insertions(+)

--- linux-2.6.23-rc3-mm1.orig/include/linux/writeback.h
+++ linux-2.6.23-rc3-mm1/include/linux/writeback.h
@@ -101,6 +101,7 @@ extern int dirty_background_ratio;
 extern int vm_dirty_ratio;
 extern int dirty_writeback_interval;
 extern int dirty_expire_interval;
+extern int dirty_volatile_interval;
 extern int block_dump;
 extern int laptop_mode;
 
--- linux-2.6.23-rc3-mm1.orig/mm/page-writeback.c
+++ linux-2.6.23-rc3-mm1/mm/page-writeback.c
@@ -85,6 +85,11 @@ int dirty_writeback_interval = 5 * HZ;
 int dirty_expire_interval = 30 * HZ;
 
 /*
+ * The shortest number of jiffies for which data should remain dirty
+ */
+int dirty_volatile_interval = 5 * HZ;
+
+/*
  * Flag that makes the machine dump writes/reads and block dirtyings.
  */
 int block_dump;
--- linux-2.6.23-rc3-mm1.orig/kernel/sysctl.c
+++ linux-2.6.23-rc3-mm1/kernel/sysctl.c
@@ -837,6 +837,13 @@ static struct ctl_table vm_table[] = {
 		.proc_handler	= &proc_dointvec_userhz_jiffies,
 	},
 	{
+		.procname	= "dirty_volatile_centisecs",
+		.data		= &dirty_volatile_interval,
+		.maxlen		= sizeof(dirty_volatile_interval),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec_userhz_jiffies,
+	},
+	{
 		.ctl_name	= VM_NR_PDFLUSH_THREADS,
 		.procname	= "nr_pdflush_threads",
 		.data		= &nr_pdflush_threads,

-- 
-
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