laptop mode for 2.4.23-pre4 and up

laptop mode for 2.4.23-pre4 and up

[Norbert Preining]

Hi Jens, hi list!

Will there be a new incantation of the laptop-mode patch for 2.4.23-pre4
and up, which includes the aa fixes. I tried to patch it in, but the
rejects in sysctl.h weren' solveable trivially.

Thanks a lot for any information and best wishes

Norbert

-------------------------------------------------------------------------------
Norbert Preining <preining AT logic DOT at>         Technische Universität Wien
gpg DSA: 0x09C5B094      fp: 14DF 2E6C 0307 BE6D AD76  A9C0 D2BF 4AA3 09C5 B094
-------------------------------------------------------------------------------
STEBBING (n.)
The erection you cannot conceal because you're not wearing a jacket.
			--- Douglas Adams, The Meaning of Liff

Re: laptop mode for 2.4.23-pre4 and up

[Jens Axboe]

On Sat, Sep 13 2003, Norbert Preining wrote:
> Hi Jens, hi list!
> 
> Will there be a new incantation of the laptop-mode patch for 2.4.23-pre4
> and up, which includes the aa fixes. I tried to patch it in, but the
> rejects in sysctl.h weren' solveable trivially.

Sure, I'll done a new patch in the next few days. I don't know what aa
patches you mean though? Are you trying to say that it conflicts with
the -aa series? It should be trivial to fix up, just renumber the
laptop-mode sysctls.

I'll send it to Marcelo too for 2.4.23.

-- 
Jens Axboe

Re: laptop mode for 2.4.23-pre4 and up

[Norbert Preining]

On Son, 14 Sep 2003, Jens Axboe wrote:
> > Will there be a new incantation of the laptop-mode patch for 2.4.23-pre4
> 
> Sure, I'll done a new patch in the next few days. I don't know what aa
> patches you mean though? Are you trying to say that it conflicts with

The ones included into kernel 2.4.23-pre4 (stuff from -aa kernels).

> the -aa series? It should be trivial to fix up, just renumber the
> laptop-mode sysctls.

Ok, this was what I wanted to know. The rest I can do myself, thanks.

> I'll send it to Marcelo too for 2.4.23.

Good idea!

Best wishes

Norbert

-------------------------------------------------------------------------------
Norbert Preining <preining AT logic DOT at>         Technische Universität Wien
gpg DSA: 0x09C5B094      fp: 14DF 2E6C 0307 BE6D AD76  A9C0 D2BF 4AA3 09C5 B094
-------------------------------------------------------------------------------
DORRIDGE (n.)
Technical term for one of the lame excuses written in very small print
on the side of packets of food or washing powder to explain why
there's hardly anything inside. Examples include 'Contents may have
settled in transit' and 'To keep each biscuit fresh they have been
individually wrapped in silver paper and cellophane and separated with
corrugated lining, a cardboard flap, and heavy industrial tyres'.
			--- Douglas Adams, The Meaning of Liff

Re: laptop mode for 2.4.23-pre4 and up

[Jens Axboe]

[-- Attachment #1: Type: text/plain, Size: 548 bytes --]

On Mon, Sep 15 2003, Norbert Preining wrote:
> On Son, 14 Sep 2003, Jens Axboe wrote:
> > > Will there be a new incantation of the laptop-mode patch for 2.4.23-pre4
> > 
> > Sure, I'll done a new patch in the next few days. I don't know what aa
> > patches you mean though? Are you trying to say that it conflicts with
> 
> The ones included into kernel 2.4.23-pre4 (stuff from -aa kernels).

Here's a fresh one against current BK, could you please give it a go?

> > I'll send it to Marcelo too for 2.4.23.
> 
> Good idea!

Done.

-- 
Jens Axboe


[-- Attachment #2: laptop-mode-2.4-bk --]
[-- Type: text/plain, Size: 11616 bytes --]

# This is a BitKeeper generated patch for the following project:
# Project Name: Linux kernel tree
# This patch format is intended for GNU patch command version 2.5 or higher.
# This patch includes the following deltas:
#	           ChangeSet	1.1135  -> 1.1136 
#	include/linux/sysctl.h	1.32    -> 1.33   
#	     kernel/sysctl.c	1.27    -> 1.28   
#	drivers/block/ll_rw_blk.c	1.50    -> 1.51   
#	    fs/jbd/journal.c	1.12    -> 1.13   
#	  include/linux/fs.h	1.89    -> 1.90   
#	        mm/filemap.c	1.88    -> 1.89   
#	         fs/buffer.c	1.95    -> 1.96   
#	               (new)	        -> 1.1     Documentation/laptop-mode.txt
#
# The following is the BitKeeper ChangeSet Log
# --------------------------------------------
# 03/09/17	axboe@smithers.home.kernel.dk	1.1136
# laptop mode
# --------------------------------------------
#
diff -Nru a/Documentation/laptop-mode.txt b/Documentation/laptop-mode.txt
--- /dev/null	Wed Dec 31 16:00:00 1969
+++ b/Documentation/laptop-mode.txt	Wed Sep 17 09:13:20 2003
@@ -0,0 +1,72 @@
+Laptop mode
+===========
+
+This small doc describes the 2.4 laptop mode patch.
+
+Last updated 2003-05-25, Jens Axboe <axboe@suse.de>
+
+Introduction
+------------
+
+A few properties of the Linux vm makes it virtually impossible to attempt
+to spin down the hard drive in a laptop for a longer period of time (more
+than a handful of seconds). This means you are lucky if you can even reach
+the break even point with regards to power consumption, let alone expect any
+decrease.
+
+One problem is the age time of dirty buffers. Linux uses 30 seconds per
+default, so if you dirty any data then flusing of that data will commence
+at most 30 seconds from then. Another is the journal commit interval of
+journalled file systems such as ext3, which is 5 seconds on a stock kernel.
+Both of these are tweakable either from proc/sysctl or as mount options
+though, and thus partly solvable from user space.
+
+The kernel update daemon (kupdated) also runs at specific intervals, flushing
+old dirty data out. Default is every 5 seconds, this too can be tweaked
+from sysctl.
+
+So what does the laptop mode patch do? It attempts to fully utilize the
+hard drive once it has been spun up, flushing the old dirty data out to
+disk. Instead of flushing just the expired data, it will clean everything.
+When a read causes the disk to spin up, we kick off this flushing after
+a few seconds. This means that once the disk spins down again, everything
+is up to date. That allows longer dirty data and journal expire times.
+
+It follows that you have to set long expire times to get long spin downs.
+This means you could potentially loose 10 minutes worth of data, if you
+set a 10 minute expire count instead of just 30 seconds worth. The biggest
+risk here is undoubtedly running out of battery.
+
+Settings
+--------
+
+The main knob is /proc/sys/vm/laptop_mode. Setting that to 1 switches the
+vm (and block layer) to laptop mode. Leaving it to 0 makes the kernel work
+like before. When in laptop mode, you also want to extend the intervals
+desribed above. See the laptop-mode.sh script for how to do that.
+
+It can happen that the disk still keeps spinning up and you don't quite
+know why or what causes it. The laptop mode patch has a little helper for
+that as well, /proc/sys/vm/block_dump. When set to 1, it will dump info to
+the kernel message buffer about what process caused the io. Be very careful
+when playing with this setting, it is advisable to shut down syslog first!
+
+Result
+------
+
+Using the laptop-mode.sh script with its default settings, I get the full
+10 minutes worth of drive spin down. Provided your work load is cached,
+the disk will only spin up every 10 minutes (well actually, 9 minutes and 55
+seconds due to the 5 second delay in flushing dirty data after the last read
+completes). I can't tell you exactly how much extra battery life you will
+gain in laptop mode, it will vary greatly on the laptop and workload in
+question. The only way to know for sure is to try it out. Getting 10% extra
+battery life is not unrealistic.
+
+Notes
+-----
+
+Patch only changes journal expire time for ext3. reiserfs uses a hardwire
+value, should be trivial to adapt though (basically just make it call
+get_buffer_flushtime() and uses that). I have not looked at other
+journalling file systems, I'll happily accept patches to rectify that!
diff -Nru a/drivers/block/ll_rw_blk.c b/drivers/block/ll_rw_blk.c
--- a/drivers/block/ll_rw_blk.c	Wed Sep 17 09:13:20 2003
+++ b/drivers/block/ll_rw_blk.c	Wed Sep 17 09:13:20 2003
@@ -121,6 +121,10 @@
 unsigned long blk_max_low_pfn, blk_max_pfn;
 int blk_nohighio = 0;
 
+int block_dump = 0;
+
+static struct timer_list writeback_timer;
+
 static inline int get_max_sectors(kdev_t dev)
 {
 	if (!max_sectors[MAJOR(dev)])
@@ -1293,6 +1297,9 @@
 	if (waitqueue_active(&bh->b_wait))
 		wake_up(&bh->b_wait);
 
+	if (block_dump)
+		printk(KERN_DEBUG "%s: %s block %lu/%u on %s\n", current->comm, rw == WRITE ? "WRITE" : "READ", bh->b_rsector, count, kdevname(bh->b_rdev));
+
 	put_bh(bh);
 	switch (rw) {
 		case WRITE:
@@ -1413,6 +1420,11 @@
 extern int stram_device_init (void);
 #endif
 
+static void blk_writeback_timer(unsigned long data)
+{
+	wakeup_bdflush();
+	wakeup_kupdate();
+}
 
 /**
  * end_that_request_first - end I/O on one buffer.
@@ -1469,10 +1481,18 @@
 	return 0;
 }
 
+extern int laptop_mode;
+
 void end_that_request_last(struct request *req)
 {
 	struct completion *waiting = req->waiting;
 
+	/*
+	 * schedule the writeout of pending dirty data when the disk is idle
+	 */
+	if (laptop_mode && req->cmd == READ)
+		mod_timer(&writeback_timer, jiffies + 5 * HZ);
+
 	req_finished_io(req);
 	blkdev_release_request(req);
 	if (waiting)
@@ -1499,6 +1519,9 @@
 
 	blk_max_low_pfn = max_low_pfn - 1;
 	blk_max_pfn = max_pfn - 1;
+
+	init_timer(&writeback_timer);
+	writeback_timer.function = blk_writeback_timer;
 
 #ifdef CONFIG_AMIGA_Z2RAM
 	z2_init();
diff -Nru a/fs/buffer.c b/fs/buffer.c
--- a/fs/buffer.c	Wed Sep 17 09:13:20 2003
+++ b/fs/buffer.c	Wed Sep 17 09:13:20 2003
@@ -88,6 +88,13 @@
 static int osync_buffers_list(struct list_head *);
 static void __refile_buffer(struct buffer_head *);
 
+/*
+ * A global sysctl-controlled flag which puts the machine into "laptop mode"
+ */
+int laptop_mode;
+
+static DECLARE_WAIT_QUEUE_HEAD(kupdate_wait);
+
 /* This is used by some architectures to estimate available memory. */
 atomic_t buffermem_pages = ATOMIC_INIT(0);
 
@@ -1016,7 +1023,7 @@
 	dirty *= 100;
 	dirty_limit = tot * bdf_prm.b_un.nfract_stop_bdflush;
 
-	if (dirty > dirty_limit)
+	if (!laptop_mode && dirty > dirty_limit)
 		return 0;
 	return 1;
 }
@@ -1066,6 +1073,8 @@
 void mark_buffer_dirty(struct buffer_head *bh)
 {
 	if (!atomic_set_buffer_dirty(bh)) {
+		if (block_dump)
+			printk("%s: dirtied buffer\n", current->comm);
 		__mark_dirty(bh);
 		balance_dirty();
 	}
@@ -1077,6 +1086,12 @@
 }
 EXPORT_SYMBOL(set_buffer_flushtime);
 
+inline int get_buffer_flushtime(void)
+{
+	return bdf_prm.b_un.age_buffer;
+}
+EXPORT_SYMBOL(get_buffer_flushtime);
+
 /*
  * A buffer may need to be moved from one buffer list to another
  * (e.g. in case it is not shared any more). Handle this.
@@ -2860,6 +2875,12 @@
 	wake_up_interruptible(&bdflush_wait);
 }
 
+void wakeup_kupdate(void)
+{
+	if (waitqueue_active(&kupdate_wait))
+		wake_up(&kupdate_wait);
+}
+
 /* 
  * Here we attempt to write back old buffers.  We also try to flush inodes 
  * and supers as well, since this function is essentially "update", and 
@@ -2880,7 +2901,9 @@
 
 		spin_lock(&lru_list_lock);
 		bh = lru_list[BUF_DIRTY];
-		if (!bh || time_before(jiffies, bh->b_flushtime))
+		if (!bh)
+			break;
+		if (time_before(jiffies, bh->b_flushtime) && !laptop_mode)
 			break;
 		if (write_some_buffers(NODEV))
 			continue;
@@ -3028,16 +3051,20 @@
 	complete((struct completion *)startup);
 
 	for (;;) {
+		DECLARE_WAITQUEUE(wait, tsk);
+
+		add_wait_queue(&kupdate_wait, &wait);
+
 		/* update interval */
 		interval = bdf_prm.b_un.interval;
 		if (interval) {
 			tsk->state = TASK_INTERRUPTIBLE;
 			schedule_timeout(interval);
 		} else {
-		stop_kupdate:
 			tsk->state = TASK_STOPPED;
 			schedule(); /* wait for SIGCONT */
 		}
+		remove_wait_queue(&kupdate_wait, &wait);
 		/* check for sigstop */
 		if (signal_pending(tsk)) {
 			int stopped = 0;
@@ -3048,13 +3075,17 @@
 			}
 			recalc_sigpending(tsk);
 			spin_unlock_irq(&tsk->sigmask_lock);
-			if (stopped)
-				goto stop_kupdate;
+			if (stopped) {
+				tsk->state = TASK_STOPPED;
+				schedule(); /* wait for SIGCONT */
+			}
 		}
 #ifdef DEBUG
 		printk(KERN_DEBUG "kupdate() activated...\n");
 #endif
 		sync_old_buffers();
+		if (laptop_mode)
+			fsync_dev(NODEV);
 		run_task_queue(&tq_disk);
 	}
 }
diff -Nru a/fs/jbd/journal.c b/fs/jbd/journal.c
--- a/fs/jbd/journal.c	Wed Sep 17 09:13:20 2003
+++ b/fs/jbd/journal.c	Wed Sep 17 09:13:20 2003
@@ -705,7 +705,7 @@
 	init_MUTEX(&journal->j_checkpoint_sem);
 	init_MUTEX(&journal->j_sem);
 
-	journal->j_commit_interval = (HZ * 5);
+	journal->j_commit_interval = get_buffer_flushtime();
 
 	/* The journal is marked for error until we succeed with recovery! */
 	journal->j_flags = JFS_ABORT;
diff -Nru a/include/linux/fs.h b/include/linux/fs.h
--- a/include/linux/fs.h	Wed Sep 17 09:13:20 2003
+++ b/include/linux/fs.h	Wed Sep 17 09:13:20 2003
@@ -1255,6 +1255,7 @@
 }
 
 extern void set_buffer_flushtime(struct buffer_head *);
+extern inline int get_buffer_flushtime(void);
 extern void balance_dirty(void);
 extern int check_disk_change(kdev_t);
 extern int invalidate_inodes(struct super_block *);
@@ -1445,8 +1446,10 @@
 	return get_hash_table(sb->s_dev, block, sb->s_blocksize);
 }
 extern void wakeup_bdflush(void);
+extern void wakeup_kupdate(void);
 extern void put_unused_buffer_head(struct buffer_head * bh);
 extern struct buffer_head * get_unused_buffer_head(int async);
+extern int block_dump;
 
 extern int brw_page(int, struct page *, kdev_t, int [], int);
 
diff -Nru a/include/linux/sysctl.h b/include/linux/sysctl.h
--- a/include/linux/sysctl.h	Wed Sep 17 09:13:20 2003
+++ b/include/linux/sysctl.h	Wed Sep 17 09:13:20 2003
@@ -154,6 +154,8 @@
 	VM_GFP_DEBUG=18,        /* debug GFP failures */
 	VM_CACHE_SCAN_RATIO=19, /* part of the inactive cache list to scan */
 	VM_MAPPED_RATIO=20,     /* amount of unfreeable pages that triggers swapout */
+	VM_LAPTOP_MODE=21,	/* kernel in laptop flush mode */
+	VM_BLOCK_DUMP=22,	/* dump fs activity to log */
 };
 
 
diff -Nru a/kernel/sysctl.c b/kernel/sysctl.c
--- a/kernel/sysctl.c	Wed Sep 17 09:13:20 2003
+++ b/kernel/sysctl.c	Wed Sep 17 09:13:20 2003
@@ -53,6 +53,8 @@
 extern int core_setuid_ok;
 extern char core_pattern[];
 extern int cad_pid;
+extern int laptop_mode;
+extern int block_dump;
 
 /* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */
 static int maxolduid = 65535;
@@ -306,6 +308,10 @@
 	&vm_max_readahead,sizeof(int), 0644, NULL, &proc_dointvec},
 	{VM_MAX_MAP_COUNT, "max_map_count",
 	 &max_map_count, sizeof(int), 0644, NULL, &proc_dointvec},
+	{VM_LAPTOP_MODE, "laptop_mode",
+	 &laptop_mode, sizeof(int), 0644, NULL, &proc_dointvec},
+	{VM_BLOCK_DUMP, "block_dump",
+	 &block_dump, sizeof(int), 0644, NULL, &proc_dointvec},
 	{0}
 };
 
diff -Nru a/mm/filemap.c b/mm/filemap.c
--- a/mm/filemap.c	Wed Sep 17 09:13:20 2003
+++ b/mm/filemap.c	Wed Sep 17 09:13:20 2003
@@ -165,6 +165,8 @@
 
 			if (mapping && mapping->host)
 				mark_inode_dirty_pages(mapping->host);
+			if (block_dump)
+				printk(KERN_DEBUG "%s: dirtied page\n", current->comm);
 		}
 	}
 }

Re: laptop mode for 2.4.23-pre4 and up

[Norbert Preining]

Hi Jens!


On Mit, 17 Sep 2003, Jens Axboe wrote:
> Here's a fresh one against current BK, could you please give it a go?

I patched my 2.4.23-pre4 together with some other patches and this one
and it worked. I am still using the laptop-mode.sh script from your
original posting (echo "30 500 0 0 $AGE $AGE 60 20 0" > /proc/sys/vm/bdflush
for start etc)

> +Laptop mode

[...]

> +desribed above. See the laptop-mode.sh script for how to do that.

Should this script be included in the readme? 

Best wishes

Norbert

-------------------------------------------------------------------------------
Norbert Preining <preining AT logic DOT at>         Technische Universität Wien
gpg DSA: 0x09C5B094      fp: 14DF 2E6C 0307 BE6D AD76  A9C0 D2BF 4AA3 09C5 B094
-------------------------------------------------------------------------------
JAWCRAIG (n. medical)
A massive facial spasm which is brought on by being told a really
astounding piece of news. A mysterious attack of jawcraig affected
40,000 sheep in Whales in 1952.
			--- Douglas Adams, The Meaning of Liff

Re: laptop mode for 2.4.23-pre4 and up

[Pavel Machek]

Hi!

> +So what does the laptop mode patch do? It attempts to fully utilize the
> +hard drive once it has been spun up, flushing the old dirty data out to
> +disk. Instead of flushing just the expired data, it will clean everything.
> +When a read causes the disk to spin up, we kick off this flushing after
> +a few seconds. This means that once the disk spins down again, everything
> +is up to date. That allows longer dirty data and journal expire times.

Another nice touch would be to sync just before spinning down.
noflushd does that... of course it needs software-controlled
spindowns.

-- 
				Pavel
Written on sharp zaurus, because my Velo1 broke. If you have Velo you don't need...

Re: laptop mode for 2.4.23-pre4 and up

[Peter Chubb]

>>>>> "Jens" == Jens Axboe <axboe@suse.de> writes:

Jens> On Mon, Sep 15 2003, Norbert Preining wrote:
>> On Son, 14 Sep 2003, Jens Axboe wrote: > > Will there be a new
>> incantation of the laptop-mode patch for 2.4.23-pre4
>> > 
>> > Sure, I'll done a new patch in the next few days. 

Are you thinking of pushing something like this into 2.6 as well?
I ask, because 2.6 seems to drive the laptop significantly harder than
2.4 anyway --- battery life is lower, the disk light is on more, and the
machine runs hotter.

--
Dr Peter Chubb  http://www.gelato.unsw.edu.au  peterc AT gelato.unsw.edu.au
You are lost in a maze of BitKeeper repositories,   all slightly different.

Re: laptop mode for 2.4.23-pre4 and up

[Jens Axboe]

On Thu, Sep 18 2003, Peter Chubb wrote:
> >>>>> "Jens" == Jens Axboe <axboe@suse.de> writes:
> 
> Jens> On Mon, Sep 15 2003, Norbert Preining wrote:
> >> On Son, 14 Sep 2003, Jens Axboe wrote: > > Will there be a new
> >> incantation of the laptop-mode patch for 2.4.23-pre4
> >> > 
> >> > Sure, I'll done a new patch in the next few days. 
> 
> Are you thinking of pushing something like this into 2.6 as well?

Definitely. Andrew had a more invasive version back in 2.5.2x iirc, that
might be a good basis if someone were to look into this before me...

> I ask, because 2.6 seems to drive the laptop significantly harder than
> 2.4 anyway --- battery life is lower, the disk light is on more, and the
> machine runs hotter.

Hmm that sounds a bit strange. I just put 2.6 on my powerbook, haven't
really used it enough yet to notice a difference. I'll keep it in mind,
though.

-- 
Jens Axboe

Re: laptop mode for 2.4.23-pre4 and up

[Jens Axboe]

On Wed, Sep 17 2003, Pavel Machek wrote:
> Hi!
> 
> > +So what does the laptop mode patch do? It attempts to fully utilize the
> > +hard drive once it has been spun up, flushing the old dirty data out to
> > +disk. Instead of flushing just the expired data, it will clean everything.
> > +When a read causes the disk to spin up, we kick off this flushing after
> > +a few seconds. This means that once the disk spins down again, everything
> > +is up to date. That allows longer dirty data and journal expire times.
> 
> Another nice touch would be to sync just before spinning down.
> noflushd does that... of course it needs software-controlled
> spindowns.

Yeah, my automatic acoustic management patch did that, works well in
addition to laptop mode. It's beyond the scope of this patch though,
it's just a vm flushing control.

-- 
Jens Axboe