[patch] remove unnecessary periodic superblock logging.

[patch] remove unnecessary periodic superblock logging.

[David Chinner]

Remove periodic logging of in-core superblock counters.

xfssyncd triggers the logging of superblock counters every
30s if the filesystem is made with lazy-count=1. This will
prevent disks from idling and spinning down as there will
be a log write every 30s. With the way counter recovery
works for lazy-count=1, this code is unnecessary and provides
no real benefit, so just remove it.

Signed-off-by: Dave Chinner <dgc@sgi.com>
---
 fs/xfs/linux-2.6/xfs_super.c |    3 +--
 fs/xfs/linux-2.6/xfs_vfs.h   |    1 -
 fs/xfs/xfs_vfsops.c          |   13 -------------
 3 files changed, 1 insertion(+), 16 deletions(-)

Index: 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_super.c
===================================================================
--- 2.6.x-xfs-new.orig/fs/xfs/linux-2.6/xfs_super.c	2008-04-10 10:02:14.000000000 +1000
+++ 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_super.c	2008-04-10 10:02:58.419346393 +1000
@@ -1028,8 +1028,7 @@ xfs_sync_worker(
 	int		error;
 
 	if (!(mp->m_flags & XFS_MOUNT_RDONLY))
-		error = xfs_sync(mp, SYNC_FSDATA | SYNC_BDFLUSH | SYNC_ATTR |
-				     SYNC_REFCACHE | SYNC_SUPER);
+		error = xfs_sync(mp, SYNC_FSDATA | SYNC_BDFLUSH | SYNC_ATTR);
 	mp->m_sync_seq++;
 	wake_up(&mp->m_wait_single_sync_task);
 }
Index: 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_vfs.h
===================================================================
--- 2.6.x-xfs-new.orig/fs/xfs/linux-2.6/xfs_vfs.h	2008-04-10 10:00:25.000000000 +1000
+++ 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_vfs.h	2008-04-10 10:02:58.419346393 +1000
@@ -49,7 +49,6 @@ typedef struct bhv_vfs_sync_work {
 #define SYNC_REFCACHE		0x0040  /* prune some of the nfs ref cache */
 #define SYNC_REMOUNT		0x0080  /* remount readonly, no dummy LRs */
 #define SYNC_IOWAIT		0x0100  /* wait for all I/O to complete */
-#define SYNC_SUPER		0x0200  /* flush superblock to disk */
 
 /*
  * When remounting a filesystem read-only or freezing the filesystem,
Index: 2.6.x-xfs-new/fs/xfs/xfs_vfsops.c
===================================================================
--- 2.6.x-xfs-new.orig/fs/xfs/xfs_vfsops.c	2008-04-10 10:01:54.000000000 +1000
+++ 2.6.x-xfs-new/fs/xfs/xfs_vfsops.c	2008-04-10 10:03:35.288729547 +1000
@@ -1326,21 +1326,8 @@ xfs_syncsub(
 	}
 
 	/*
-	 * If asked, update the disk superblock with incore counter values if we
-	 * are using non-persistent counters so that they don't get too far out
-	 * of sync if we crash or get a forced shutdown. We don't want to force
-	 * this to disk, just get a transaction into the iclogs....
-	 */
-	if (flags & SYNC_SUPER) {
-		error = xfs_log_sbcount(mp, 0);
-		if (error)
-			last_error = error;
-	}
-
-	/*
 	 * Now check to see if the log needs a "dummy" transaction.
 	 */
-
 	if (!(flags & SYNC_REMOUNT) && xfs_log_need_covered(mp)) {
 		xfs_trans_t *tp;
 		xfs_inode_t *ip;

Re: [patch] remove unnecessary periodic superblock logging.

[Barry Naujok]

On Thu, 10 Apr 2008 14:20:01 +1000, David Chinner <dgc@sgi.com> wrote:

> Remove periodic logging of in-core superblock counters.
>
> xfssyncd triggers the logging of superblock counters every
> 30s if the filesystem is made with lazy-count=1. This will
> prevent disks from idling and spinning down as there will
> be a log write every 30s. With the way counter recovery
> works for lazy-count=1, this code is unnecessary and provides
> no real benefit, so just remove it.

I'm happy with this (xfs_initialize_perag_data() does the
global counter recovery during mount).

> Signed-off-by: Dave Chinner <dgc@sgi.com>
> ---
>  fs/xfs/linux-2.6/xfs_super.c |    3 +--
>  fs/xfs/linux-2.6/xfs_vfs.h   |    1 -
>  fs/xfs/xfs_vfsops.c          |   13 -------------
>  3 files changed, 1 insertion(+), 16 deletions(-)
>
> Index: 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_super.c
> ===================================================================
> --- 2.6.x-xfs-new.orig/fs/xfs/linux-2.6/xfs_super.c	2008-04-10  
> 10:02:14.000000000 +1000
> +++ 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_super.c	2008-04-10  
> 10:02:58.419346393 +1000
> @@ -1028,8 +1028,7 @@ xfs_sync_worker(
>  	int		error;
> 	if (!(mp->m_flags & XFS_MOUNT_RDONLY))
> -		error = xfs_sync(mp, SYNC_FSDATA | SYNC_BDFLUSH | SYNC_ATTR |
> -				     SYNC_REFCACHE | SYNC_SUPER);
> +		error = xfs_sync(mp, SYNC_FSDATA | SYNC_BDFLUSH | SYNC_ATTR);
>  	mp->m_sync_seq++;
>  	wake_up(&mp->m_wait_single_sync_task);
>  }
> Index: 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_vfs.h
> ===================================================================
> --- 2.6.x-xfs-new.orig/fs/xfs/linux-2.6/xfs_vfs.h	2008-04-10  
> 10:00:25.000000000 +1000
> +++ 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_vfs.h	2008-04-10  
> 10:02:58.419346393 +1000
> @@ -49,7 +49,6 @@ typedef struct bhv_vfs_sync_work {
>  #define SYNC_REFCACHE		0x0040  /* prune some of the nfs ref cache */
>  #define SYNC_REMOUNT		0x0080  /* remount readonly, no dummy LRs */
>  #define SYNC_IOWAIT		0x0100  /* wait for all I/O to complete */
> -#define SYNC_SUPER		0x0200  /* flush superblock to disk */
> /*
>   * When remounting a filesystem read-only or freezing the filesystem,
> Index: 2.6.x-xfs-new/fs/xfs/xfs_vfsops.c
> ===================================================================
> --- 2.6.x-xfs-new.orig/fs/xfs/xfs_vfsops.c	2008-04-10 10:01:54.000000000  
> +1000
> +++ 2.6.x-xfs-new/fs/xfs/xfs_vfsops.c	2008-04-10 10:03:35.288729547 +1000
> @@ -1326,21 +1326,8 @@ xfs_syncsub(
>  	}
> 	/*
> -	 * If asked, update the disk superblock with incore counter values if  
> we
> -	 * are using non-persistent counters so that they don't get too far out
> -	 * of sync if we crash or get a forced shutdown. We don't want to force
> -	 * this to disk, just get a transaction into the iclogs....
> -	 */
> -	if (flags & SYNC_SUPER) {
> -		error = xfs_log_sbcount(mp, 0);
> -		if (error)
> -			last_error = error;
> -	}
> -
> -	/*
>  	 * Now check to see if the log needs a "dummy" transaction.
>  	 */
> -
>  	if (!(flags & SYNC_REMOUNT) && xfs_log_need_covered(mp)) {
>  		xfs_trans_t *tp;
>  		xfs_inode_t *ip;
>
>

Re: [patch] remove unnecessary periodic superblock logging.

[Timothy Shimmin]

Barry Naujok wrote:
> On Thu, 10 Apr 2008 14:20:01 +1000, David Chinner <dgc@sgi.com> wrote:
> 
>> Remove periodic logging of in-core superblock counters.
>>
>> xfssyncd triggers the logging of superblock counters every
>> 30s if the filesystem is made with lazy-count=1. This will
>> prevent disks from idling and spinning down as there will
>> be a log write every 30s. With the way counter recovery
>> works for lazy-count=1, this code is unnecessary and provides
>> no real benefit, so just remove it.
> 
> I'm happy with this (xfs_initialize_perag_data() does the
> global counter recovery during mount).
> 

So we only do the sb count logging at unmount type times...
xfs_attr_quiesce() and xfs_unmountfs(),
when no log recovery will happen.
Hmmm...so why do we have to log it out at these times?
I'm forgetting how this works.

--Tim


>> Signed-off-by: Dave Chinner <dgc@sgi.com>
>> ---
>>  fs/xfs/linux-2.6/xfs_super.c |    3 +--
>>  fs/xfs/linux-2.6/xfs_vfs.h   |    1 -
>>  fs/xfs/xfs_vfsops.c          |   13 -------------
>>  3 files changed, 1 insertion(+), 16 deletions(-)
>>
>> Index: 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_super.c
>> ===================================================================
>> --- 2.6.x-xfs-new.orig/fs/xfs/linux-2.6/xfs_super.c    2008-04-10 
>> 10:02:14.000000000 +1000
>> +++ 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_super.c    2008-04-10 
>> 10:02:58.419346393 +1000
>> @@ -1028,8 +1028,7 @@ xfs_sync_worker(
>>      int        error;
>>     if (!(mp->m_flags & XFS_MOUNT_RDONLY))
>> -        error = xfs_sync(mp, SYNC_FSDATA | SYNC_BDFLUSH | SYNC_ATTR |
>> -                     SYNC_REFCACHE | SYNC_SUPER);
>> +        error = xfs_sync(mp, SYNC_FSDATA | SYNC_BDFLUSH | SYNC_ATTR);
>>      mp->m_sync_seq++;
>>      wake_up(&mp->m_wait_single_sync_task);
>>  }
>> Index: 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_vfs.h
>> ===================================================================
>> --- 2.6.x-xfs-new.orig/fs/xfs/linux-2.6/xfs_vfs.h    2008-04-10 
>> 10:00:25.000000000 +1000
>> +++ 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_vfs.h    2008-04-10 
>> 10:02:58.419346393 +1000
>> @@ -49,7 +49,6 @@ typedef struct bhv_vfs_sync_work {
>>  #define SYNC_REFCACHE        0x0040  /* prune some of the nfs ref 
>> cache */
>>  #define SYNC_REMOUNT        0x0080  /* remount readonly, no dummy LRs */
>>  #define SYNC_IOWAIT        0x0100  /* wait for all I/O to complete */
>> -#define SYNC_SUPER        0x0200  /* flush superblock to disk */
>> /*
>>   * When remounting a filesystem read-only or freezing the filesystem,
>> Index: 2.6.x-xfs-new/fs/xfs/xfs_vfsops.c
>> ===================================================================
>> --- 2.6.x-xfs-new.orig/fs/xfs/xfs_vfsops.c    2008-04-10 
>> 10:01:54.000000000 +1000
>> +++ 2.6.x-xfs-new/fs/xfs/xfs_vfsops.c    2008-04-10 10:03:35.288729547 
>> +1000
>> @@ -1326,21 +1326,8 @@ xfs_syncsub(
>>      }
>>     /*
>> -     * If asked, update the disk superblock with incore counter 
>> values if we
>> -     * are using non-persistent counters so that they don't get too 
>> far out
>> -     * of sync if we crash or get a forced shutdown. We don't want to 
>> force
>> -     * this to disk, just get a transaction into the iclogs....
>> -     */
>> -    if (flags & SYNC_SUPER) {
>> -        error = xfs_log_sbcount(mp, 0);
>> -        if (error)
>> -            last_error = error;
>> -    }
>> -
>> -    /*
>>       * Now check to see if the log needs a "dummy" transaction.
>>       */
>> -
>>      if (!(flags & SYNC_REMOUNT) && xfs_log_need_covered(mp)) {
>>          xfs_trans_t *tp;
>>          xfs_inode_t *ip;
>>
>>
> 
> 
> 

Re: [patch] remove unnecessary periodic superblock logging.

[David Chinner]

On Thu, Apr 10, 2008 at 03:29:30PM +1000, Timothy Shimmin wrote:
> Barry Naujok wrote:
> >On Thu, 10 Apr 2008 14:20:01 +1000, David Chinner <dgc@sgi.com> wrote:
> >
> >>Remove periodic logging of in-core superblock counters.
> >>
> >>xfssyncd triggers the logging of superblock counters every
> >>30s if the filesystem is made with lazy-count=1. This will
> >>prevent disks from idling and spinning down as there will
> >>be a log write every 30s. With the way counter recovery
> >>works for lazy-count=1, this code is unnecessary and provides
> >>no real benefit, so just remove it.
> >
> >I'm happy with this (xfs_initialize_perag_data() does the
> >global counter recovery during mount).
> >
> 
> So we only do the sb count logging at unmount type times...
> xfs_attr_quiesce() and xfs_unmountfs(),
> when no log recovery will happen.
> Hmmm...so why do we have to log it out at these times?
> I'm forgetting how this works.

xfs_log_sbcount() sync's the incore counters to the superblock
buffer transactionally. Not strictly necessary, but for consistency
with other superblock updates.....

Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group