ext3: sreadahead hooks

PATCH In review Arjan van de Ven 4 participants 6 messages Oct 14, 2008 – Oct 20, 2008

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Arjan van de Ven

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2008-10-14 14:17 UTC #0 lore raw

PATCH 1/1 ext3: sreadahead hooks

Quoted 2 lines

From 3d7a0ca0ee8a755251251bd9ddca0866c25acdc2 Mon Sep 17 00:00:00 2001

From: Arjan van de Ven <[email protected]>
Date: Tue, 14 Oct 2008 10:12:08 -0400
Subject: [PATCH] ext3: sreadahead hooks

The sreadahead program, used to make the OS boot faster, needs to know in the approximate order in files are used during the boot process. This patch adds the ext3 hook for this functionality, basically it stores "jiffies" into the inode at allocation time, and exposes it via an EXT3 ioctl (yes I know but ioctl seems fitting for this).

Signed-off-by Arjan van de Ven <[email protected]>

---
 fs/ext3/ioctl.c           |    3 +++
 fs/ext3/super.c           |    1 +
 include/linux/ext3_fs.h   |    1 +
 include/linux/ext3_fs_i.h |    2 ++
 4 files changed, 7 insertions(+), 0 deletions(-)

fs/ext3/ioctl.c +3 -0

index 0d0c701..b196f71 100644
@@ -286,6 +286,9 @@ group_add_out:
 		mnt_drop_write(filp->f_path.mnt);
 		return err;
 	}
+	case EXT3_IOC_INODE_JIFFIES: {
+		return ei->created_when;
+	}
 
 
 	default:

fs/ext3/super.c +1 -0

index f38a5af..c2c83dd 100644
@@ -456,6 +456,7 @@ static struct inode *ext3_alloc_inode(struct super_block *sb)
 #endif
 	ei->i_block_alloc_info = NULL;
 	ei->vfs_inode.i_version = 1;
+	ei->created_when = jiffies;
 	return &ei->vfs_inode;
 }

include/linux/ext3_fs.h +1 -0

index 8120fa1..d1ba6b8 100644
@@ -225,6 +225,7 @@ struct ext3_new_group_data {
 #endif
 #define EXT3_IOC_GETRSVSZ		_IOR('f', 5, long)
 #define EXT3_IOC_SETRSVSZ		_IOW('f', 6, long)
+#define EXT3_IOC_INODE_JIFFIES		_IOR('f', 19, long)
 
 /*
  * ioctl commands in 32 bit emulation

include/linux/ext3_fs_i.h +2 -0

index 7894dd0..87d512a 100644
@@ -141,6 +141,8 @@ struct ext3_inode_info {
 	 * by other means, so we have truncate_mutex.
 	 */
 	struct mutex truncate_mutex;
+	unsigned long		created_when; /* jiffies of creation time */	
+
 	struct inode vfs_inode;
 };

Signature · 7 lines

1.5.5.1


-- 
Arjan van de Ven 	Intel Open Source Technology Centre
For development, discussion and tips for power savings, 
visit http://www.lesswatts.org

Christoph Hellwig

2008-10-14 15:13 UTC #1 lore raw

Quoted 11 lines · Arjan van de Ven

Quoted 2 lines
From 3d7a0ca0ee8a755251251bd9ddca0866c25acdc2 Mon Sep 17 00:00:00 2001
From: Arjan van de Ven <[email protected]>
Date: Tue, 14 Oct 2008 10:12:08 -0400
Subject: [PATCH] ext3: sreadahead hooks
The sreadahead program, used to make the OS boot faster, needs to know in the approximate order in files are used during the boot process. This patch adds the ext3 hook for this functionality, basically it stores "jiffies" into the inode at allocation time, and exposes it via an EXT3 ioctl (yes I know but ioctl seems fitting for this).

Even if it's an ioctl there's absolutely no point in making this fileystem specific. Also the name is rather dumb and non-descriptive.

Eric Sandeen

2008-10-14 15:51 UTC #2 lore raw

Quoted 6 lines · Christoph Hellwig

Quoted 5 lines · Arjan van de Ven
Quoted 1 line
From 3d7a0ca0ee8a755251251bd9ddca0866c25acdc2 Mon Sep 17 00:00:00 2001
From: Arjan van de Ven <[email protected]>
Date: Tue, 14 Oct 2008 10:12:08 -0400
Subject: [PATCH] ext3: sreadahead hooks

Quoted 8 lines

Quoted 5 lines
The sreadahead program, used to make the OS boot faster, needs to know in the approximate order in files are used during the boot process. This patch adds the ext3 hook for this functionality, basically it stores "jiffies" into the inode at allocation time, and exposes it via an EXT3 ioctl (yes I know but ioctl seems fitting for this).
Even if it's an ioctl there's absolutely no point in making this fileystem specific. Also the name is rather dumb and non-descriptive.

I have to agree, both the ioctl name and the new field are not very descriptive - created_when sounds an awful lot like ctime but it's not.

and INODE_JIFFIES really doesn't mean anything at all w/o extra context.
But I'm trying to think of some nice names. :)

What about making a new struct inode field and doing this update in new_inode(), and making it a generic ioctl. Are we ready to go that far?

-Eric

Eric Sandeen

2008-10-14 21:49 UTC #3 lore raw

Quoted 15 lines · Eric Sandeen

Quoted 6 lines · Christoph Hellwig
Quoted 5 lines · Arjan van de Ven
Quoted 1 line
From 3d7a0ca0ee8a755251251bd9ddca0866c25acdc2 Mon Sep 17 00:00:00 2001
From: Arjan van de Ven <[email protected]>
Date: Tue, 14 Oct 2008 10:12:08 -0400
Subject: [PATCH] ext3: sreadahead hooks
Quoted 7 lines
Quoted 5 lines
The sreadahead program, used to make the OS boot faster, needs to know in the approximate order in files are used during the boot process. This patch adds the ext3 hook for this functionality, basically it stores "jiffies" into the inode at allocation time, and exposes it via an EXT3 ioctl (yes I know but ioctl seems fitting for this).
Even if it's an ioctl there's absolutely no point in making this fileystem specific. Also the name is rather dumb and non-descriptive.

Quoted 8 lines

I have to agree, both the ioctl name and the new field are not very descriptive - created_when sounds an awful lot like ctime but it's not.
and INODE_JIFFIES really doesn't mean anything at all w/o extra context.
But I'm trying to think of some nice names. :)
What about making a new struct inode field and doing this update in new_inode(), and making it a generic ioctl. Are we ready to go that far?

Or, as I thought about/mentioned to hch, and I guess he and Arjan already discussed... :) why not just use tracing infrastructure to get this info, rather than adding new members to every inode on the system?

-Eric

Karel Zak

2008-10-19 21:42 UTC #4 lore raw

Quoted 19 lines · Eric Sandeen

Quoted 18 lines · Eric Sandeen
Quoted 6 lines · Christoph Hellwig
Quoted 5 lines · Arjan van de Ven
Quoted 1 line
From 3d7a0ca0ee8a755251251bd9ddca0866c25acdc2 Mon Sep 17 00:00:00 2001
From: Arjan van de Ven <[email protected]>
Date: Tue, 14 Oct 2008 10:12:08 -0400
Subject: [PATCH] ext3: sreadahead hooks
Quoted 7 lines
Quoted 5 lines
The sreadahead program, used to make the OS boot faster, needs to know in the approximate order in files are used during the boot process. This patch adds the ext3 hook for this functionality, basically it stores "jiffies" into the inode at allocation time, and exposes it via an EXT3 ioctl (yes I know but ioctl seems fitting for this).
Even if it's an ioctl there's absolutely no point in making this fileystem specific. Also the name is rather dumb and non-descriptive.
I have to agree, both the ioctl name and the new field are not very descriptive - created_when sounds an awful lot like ctime but it's not.

Quoted 8 lines

Quoted 5 lines
and INODE_JIFFIES really doesn't mean anything at all w/o extra context.
But I'm trying to think of some nice names. :)
What about making a new struct inode field and doing this update in new_inode(), and making it a generic ioctl. Are we ready to go that far?
Or, as I thought about/mentioned to hch, and I guess he and Arjan already discussed... :) why not just use tracing infrastructure to get

What do you mean by "tracing infrastructure"? Audit?

I had the same question (especially when I'm an author of the readahead-collector that uses the audit subsystem for this task :-). The problem is that audit stuff is difficult to use (you have to disable auditd, and it's not simple to integrate it to the distribution).

Arjan's solution is extremely simple and useful without invasive changes in distributions.

Quoted 1 line

this info, rather than adding new members to every inode on the system?

#ifdef CONFIG_INODE_JIFFIES

('n' for servers which don't need to boot in 5 secs ;-)

Karel

Signature · 1 line

 Karel Zak  <[email protected]>

Arjan van de Ven

author

2008-10-20 03:51 UTC #5 lore raw

Quoted 31 lines · On Sun, 19 Oct 2008 23:42:05 +0200 Karel Zak <[email protected]> wrote:

Quoted 30 lines · Eric Sandeen
Quoted 28 lines · Eric Sandeen
Quoted 13 lines · Christoph Hellwig
Quoted 6 lines · Arjan van de Ven
Quoted 2 lines
From 3d7a0ca0ee8a755251251bd9ddca0866c25acdc2 Mon Sep 17 00:00:00 2001
From: Arjan van de Ven <[email protected]>
Date: Tue, 14 Oct 2008 10:12:08 -0400
Subject: [PATCH] ext3: sreadahead hooks
Quoted 6 lines
The sreadahead program, used to make the OS boot faster, needs to know in the approximate order in files are used during the boot process. This patch adds the ext3 hook for this functionality, basically it stores "jiffies" into the inode at allocation time, and exposes it via an EXT3 ioctl (yes I know but ioctl seems fitting for this).
Quoted 3 lines
Even if it's an ioctl there's absolutely no point in making this fileystem specific. Also the name is rather dumb and non-descriptive.
I have to agree, both the ioctl name and the new field are not very descriptive - created_when sounds an awful lot like ctime but it's not.
and INODE_JIFFIES really doesn't mean anything at all w/o extra context. But I'm trying to think of some nice names. :)
What about making a new struct inode field and doing this update in new_inode(), and making it a generic ioctl. Are we ready to go that far?

Quoted 5 lines

Quoted 3 lines
Or, as I thought about/mentioned to hch, and I guess he and Arjan already discussed... :) why not just use tracing infrastructure to get
What do you mean by "tracing infrastructure"? Audit?

ftrace

I'll be looking into making that one work soon; it'll be... interesting and more complex than this patch, but if that's what it takes...

Signature · 3 lines

Arjan van de Ven 	Intel Open Source Technology Centre
For development, discussion and tips for power savings, 
visit http://www.lesswatts.org