Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=195cf453d2c3d789cbe80e3735755f860c2fb222
Commit: 195cf453d2c3d789cbe80e3735755f860c2fb222
Parent: 3dfa5721f12c3d5a441448086bee156887daa961
Author: Bron Gondwana <[EMAIL PROTECTED]>
AuthorDate: Mon Feb 4 22:29:20 2008 -0800
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Tue Feb 5 09:44:18 2008 -0800
mm/page-writeback: highmem_is_dirtyable option
Add vm.highmem_is_dirtyable toggle
A 32 bit machine with HIGHMEM64 enabled running DCC has an MMAPed file of
approximately 2Gb size which contains a hash format that is written
randomly by the dbclean process. On 2.6.16 this process took a few
minutes. With lowmem only accounting of dirty ratios, this takes about 12
hours of 100% disk IO, all random writes.
Include a toggle in /proc/sys/vm/highmem_is_dirtyable which can be set to 1
to
add the highmem back to the total available memory count.
[EMAIL PROTECTED]: Fix the CONFIG_DETECT_SOFTLOCKUP=y build]
Signed-off-by: Bron Gondwana <[EMAIL PROTECTED]>
Cc: Ethan Solomita <[EMAIL PROTECTED]>
Cc: Peter Zijlstra <[EMAIL PROTECTED]>
Cc: WU Fengguang <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
Documentation/filesystems/proc.txt | 15 +++++++++++++++
Documentation/sysctl/vm.txt | 7 ++++---
include/linux/writeback.h | 1 +
kernel/sysctl.c | 18 +++++++++++++++++-
mm/page-writeback.c | 11 ++++++++++-
5 files changed, 47 insertions(+), 5 deletions(-)
diff --git a/Documentation/filesystems/proc.txt
b/Documentation/filesystems/proc.txt
index 0b1b0c0..07231af 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -1315,6 +1315,21 @@ for writeout by the pdflush daemons. It is expressed in
100'ths of a second.
Data which has been dirty in-memory for longer than this interval will be
written out next time a pdflush daemon wakes up.
+highmem_is_dirtyable
+--------------------
+
+Only present if CONFIG_HIGHMEM is set.
+
+This defaults to 0 (false), meaning that the ratios set above are calculated
+as a percentage of lowmem only. This protects against excessive scanning
+in page reclaim, swapping and general VM distress.
+
+Setting this to 1 can be useful on 32 bit machines where you want to make
+random changes within an MMAPed file that is larger than your available
+lowmem without causing large quantities of random IO. Is is safe if the
+behavior of all programs running on the machine is known and memory will
+not be otherwise stressed.
+
legacy_va_layout
----------------
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 6f31f0a..24eac1b 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -22,6 +22,7 @@ Currently, these files are in /proc/sys/vm:
- dirty_background_ratio
- dirty_expire_centisecs
- dirty_writeback_centisecs
+- highmem_is_dirtyable (only if CONFIG_HIGHMEM set)
- max_map_count
- min_free_kbytes
- laptop_mode
@@ -40,9 +41,9 @@ Currently, these files are in /proc/sys/vm:
==============================================================
dirty_ratio, dirty_background_ratio, dirty_expire_centisecs,
-dirty_writeback_centisecs, vfs_cache_pressure, laptop_mode,
-block_dump, swap_token_timeout, drop-caches,
-hugepages_treat_as_movable:
+dirty_writeback_centisecs, highmem_is_dirtyable,
+vfs_cache_pressure, laptop_mode, block_dump, swap_token_timeout,
+drop-caches, hugepages_treat_as_movable:
See Documentation/filesystems/proc.txt
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index c6148bb..b2cd826 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -100,6 +100,7 @@ extern int dirty_background_ratio;
extern int vm_dirty_ratio;
extern int dirty_writeback_interval;
extern int dirty_expire_interval;
+extern int vm_highmem_is_dirtyable;
extern int block_dump;
extern int laptop_mode;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 7cb1ac3..d0b47b8 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -84,8 +84,11 @@ extern int sysctl_stat_interval;
extern int latencytop_enabled;
/* Constants used for minimum and maximum */
-#ifdef CONFIG_DETECT_SOFTLOCKUP
+#if defined(CONFIG_DETECT_SOFTLOCKUP) || defined(CONFIG_HIGHMEM)
static int one = 1;
+#endif
+
+#ifdef CONFIG_DETECT_SOFTLOCKUP
static int sixty = 60;
#endif
@@ -1150,6 +1153,19 @@ static struct ctl_table vm_table[] = {
.extra1 = &zero,
},
#endif
+#ifdef CONFIG_HIGHMEM
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "highmem_is_dirtyable",
+ .data = &vm_highmem_is_dirtyable,
+ .maxlen = sizeof(vm_highmem_is_dirtyable),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec_minmax,
+ .strategy = &sysctl_intvec,
+ .extra1 = &zero,
+ .extra2 = &one,
+ },
+#endif
/*
* NOTE: do not add new entries to this table unless you have read
* Documentation/sysctl/ctl_unnumbered.txt
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 8137482..c689b60 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -69,6 +69,12 @@ static inline long sync_writeback_pages(void)
int dirty_background_ratio = 5;
/*
+ * free highmem will not be subtracted from the total free memory
+ * for calculating free ratios if vm_highmem_is_dirtyable is true
+ */
+int vm_highmem_is_dirtyable;
+
+/*
* The generator of dirty data starts writeback at this percentage
*/
int vm_dirty_ratio = 10;
@@ -287,7 +293,10 @@ static unsigned long determine_dirtyable_memory(void)
x = global_page_state(NR_FREE_PAGES)
+ global_page_state(NR_INACTIVE)
+ global_page_state(NR_ACTIVE);
- x -= highmem_dirtyable_memory(x);
+
+ if (!vm_highmem_is_dirtyable)
+ x -= highmem_dirtyable_memory(x);
+
return x + 1; /* Ensure that we never return 0 */
}
-
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