[PATCH] Remove incorrect usage of sysctl_vfs_cache_pressure

[PATCH] Remove incorrect usage of sysctl_vfs_cache_pressure

[raghu.prabhu13]

From: Raghavendra D Prabhu <rprabhu@wnohang.net>

In shrinker functions, sysctl_vfs_cache_pressure variable is being used while
trimming slab caches in general and not restricted to inode/dentry caches as
documented for that sysctl.

Raghavendra D Prabhu (1):
  mm/vmscan: Remove sysctl_vfs_cache_pressure from non-vfs shrinkers

 drivers/gpu/drm/i915/i915_gem.c |    2 +-
 fs/gfs2/glock.c                 |    2 +-
 fs/gfs2/quota.c                 |    2 +-
 fs/mbcache.c                    |    2 +-
 fs/nfs/dir.c                    |    2 +-
 fs/quota/dquot.c                |    3 +--
 net/sunrpc/auth.c               |    2 +-
 7 files changed, 7 insertions(+), 8 deletions(-)

-- 
1.7.6

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[PATCH] mm/vmscan: Remove sysctl_vfs_cache_pressure from non-vfs shrinkers

[raghu.prabhu13]

From: Raghavendra D Prabhu <rprabhu@wnohang.net>

sysctl_vfs_cache_pressure is meant to only affect the dentries and inodes slab
caches. However, it has been used shrinkers elsewhere to trim the number of
slabs returned to shrink_slab. So, this patch removes it from those places.

Signed-off-by: Raghavendra D Prabhu <rprabhu@wnohang.net>
---
 drivers/gpu/drm/i915/i915_gem.c |    2 +-
 fs/gfs2/glock.c                 |    2 +-
 fs/gfs2/quota.c                 |    2 +-
 fs/mbcache.c                    |    2 +-
 fs/nfs/dir.c                    |    2 +-
 fs/quota/dquot.c                |    3 +--
 net/sunrpc/auth.c               |    2 +-
 7 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 5c0d124..ca4f6b5 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4146,5 +4146,5 @@ rescan:
 			goto rescan;
 	}
 	mutex_unlock(&dev->struct_mutex);
-	return cnt / 100 * sysctl_vfs_cache_pressure;
+	return cnt;
 }
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 1c1336e..68872ed 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -1400,7 +1400,7 @@ static int gfs2_shrink_glock_memory(struct shrinker *shrink,
 	atomic_add(nr_skipped, &lru_count);
 	spin_unlock(&lru_lock);
 out:
-	return (atomic_read(&lru_count) / 100) * sysctl_vfs_cache_pressure;
+	return atomic_read(&lru_count);
 }
 
 static struct shrinker glock_shrinker = {
diff --git a/fs/gfs2/quota.c b/fs/gfs2/quota.c
index 42e8d23..30ac1fa 100644
--- a/fs/gfs2/quota.c
+++ b/fs/gfs2/quota.c
@@ -117,7 +117,7 @@ int gfs2_shrink_qd_memory(struct shrinker *shrink, struct shrink_control *sc)
 	spin_unlock(&qd_lru_lock);
 
 out:
-	return (atomic_read(&qd_lru_count) * sysctl_vfs_cache_pressure) / 100;
+	return atomic_read(&qd_lru_count);
 }
 
 static u64 qd2offset(struct gfs2_quota_data *qd)
diff --git a/fs/mbcache.c b/fs/mbcache.c
index 8c32ef3..2a51c51 100644
--- a/fs/mbcache.c
+++ b/fs/mbcache.c
@@ -189,7 +189,7 @@ mb_cache_shrink_fn(struct shrinker *shrink, struct shrink_control *sc)
 	list_for_each_entry_safe(entry, tmp, &free_list, e_lru_list) {
 		__mb_cache_entry_forget(entry, gfp_mask);
 	}
-	return (count / 100) * sysctl_vfs_cache_pressure;
+	return count;
 }
 
 
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index ededdbd..700806e 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -2077,7 +2077,7 @@ remove_lru_entry:
 	}
 	spin_unlock(&nfs_access_lru_lock);
 	nfs_access_free_list(&head);
-	return (atomic_long_read(&nfs_access_nr_entries) / 100) * sysctl_vfs_cache_pressure;
+	return atomic_long_read(&nfs_access_nr_entries);
 }
 
 static void __nfs_access_zap_cache(struct nfs_inode *nfsi, struct list_head *head)
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 5b572c8..97dd902 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -702,8 +702,7 @@ static int shrink_dqcache_memory(struct shrinker *shrink,
 		spin_unlock(&dq_list_lock);
 	}
 	return ((unsigned)
-		percpu_counter_read_positive(&dqstats.counter[DQST_FREE_DQUOTS])
-		/100) * sysctl_vfs_cache_pressure;
+		percpu_counter_read_positive(&dqstats.counter[DQST_FREE_DQUOTS]));
 }
 
 static struct shrinker dqcache_shrinker = {
diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
index cd6e4aa..8f53697 100644
--- a/net/sunrpc/auth.c
+++ b/net/sunrpc/auth.c
@@ -319,7 +319,7 @@ rpcauth_prune_expired(struct list_head *free, int nr_to_scan)
 		}
 		spin_unlock(cache_lock);
 	}
-	return (number_cred_unused / 100) * sysctl_vfs_cache_pressure;
+	return number_cred_unused;
 }
 
 /*
-- 
1.7.6

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Re: [PATCH] mm/vmscan: Remove sysctl_vfs_cache_pressure from non-vfs shrinkers

[KAMEZAWA Hiroyuki]

On Mon, 11 Jul 2011 02:56:24 +0530
raghu.prabhu13@gmail.com wrote:

> From: Raghavendra D Prabhu <rprabhu@wnohang.net>
> 
> sysctl_vfs_cache_pressure is meant to only affect the dentries and inodes slab
> caches. However, it has been used shrinkers elsewhere to trim the number of
> slabs returned to shrink_slab. So, this patch removes it from those places.
> 
> Signed-off-by: Raghavendra D Prabhu <rprabhu@wnohang.net>

Hmm, which is better to fix the code or to fix the Document ?

Thanks,
-Kame



> ---
>  drivers/gpu/drm/i915/i915_gem.c |    2 +-
>  fs/gfs2/glock.c                 |    2 +-
>  fs/gfs2/quota.c                 |    2 +-
>  fs/mbcache.c                    |    2 +-
>  fs/nfs/dir.c                    |    2 +-
>  fs/quota/dquot.c                |    3 +--
>  net/sunrpc/auth.c               |    2 +-
>  7 files changed, 7 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 5c0d124..ca4f6b5 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -4146,5 +4146,5 @@ rescan:
>  			goto rescan;
>  	}
>  	mutex_unlock(&dev->struct_mutex);
> -	return cnt / 100 * sysctl_vfs_cache_pressure;
> +	return cnt;
>  }
> diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
> index 1c1336e..68872ed 100644
> --- a/fs/gfs2/glock.c
> +++ b/fs/gfs2/glock.c
> @@ -1400,7 +1400,7 @@ static int gfs2_shrink_glock_memory(struct shrinker *shrink,
>  	atomic_add(nr_skipped, &lru_count);
>  	spin_unlock(&lru_lock);
>  out:
> -	return (atomic_read(&lru_count) / 100) * sysctl_vfs_cache_pressure;
> +	return atomic_read(&lru_count);
>  }
>  
>  static struct shrinker glock_shrinker = {
> diff --git a/fs/gfs2/quota.c b/fs/gfs2/quota.c
> index 42e8d23..30ac1fa 100644
> --- a/fs/gfs2/quota.c
> +++ b/fs/gfs2/quota.c
> @@ -117,7 +117,7 @@ int gfs2_shrink_qd_memory(struct shrinker *shrink, struct shrink_control *sc)
>  	spin_unlock(&qd_lru_lock);
>  
>  out:
> -	return (atomic_read(&qd_lru_count) * sysctl_vfs_cache_pressure) / 100;
> +	return atomic_read(&qd_lru_count);
>  }
>  
>  static u64 qd2offset(struct gfs2_quota_data *qd)
> diff --git a/fs/mbcache.c b/fs/mbcache.c
> index 8c32ef3..2a51c51 100644
> --- a/fs/mbcache.c
> +++ b/fs/mbcache.c
> @@ -189,7 +189,7 @@ mb_cache_shrink_fn(struct shrinker *shrink, struct shrink_control *sc)
>  	list_for_each_entry_safe(entry, tmp, &free_list, e_lru_list) {
>  		__mb_cache_entry_forget(entry, gfp_mask);
>  	}
> -	return (count / 100) * sysctl_vfs_cache_pressure;
> +	return count;
>  }
>  
>  
> diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
> index ededdbd..700806e 100644
> --- a/fs/nfs/dir.c
> +++ b/fs/nfs/dir.c
> @@ -2077,7 +2077,7 @@ remove_lru_entry:
>  	}
>  	spin_unlock(&nfs_access_lru_lock);
>  	nfs_access_free_list(&head);
> -	return (atomic_long_read(&nfs_access_nr_entries) / 100) * sysctl_vfs_cache_pressure;
> +	return atomic_long_read(&nfs_access_nr_entries);
>  }
>  
>  static void __nfs_access_zap_cache(struct nfs_inode *nfsi, struct list_head *head)
> diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
> index 5b572c8..97dd902 100644
> --- a/fs/quota/dquot.c
> +++ b/fs/quota/dquot.c
> @@ -702,8 +702,7 @@ static int shrink_dqcache_memory(struct shrinker *shrink,
>  		spin_unlock(&dq_list_lock);
>  	}
>  	return ((unsigned)
> -		percpu_counter_read_positive(&dqstats.counter[DQST_FREE_DQUOTS])
> -		/100) * sysctl_vfs_cache_pressure;
> +		percpu_counter_read_positive(&dqstats.counter[DQST_FREE_DQUOTS]));
>  }
>  
>  static struct shrinker dqcache_shrinker = {
> diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
> index cd6e4aa..8f53697 100644
> --- a/net/sunrpc/auth.c
> +++ b/net/sunrpc/auth.c
> @@ -319,7 +319,7 @@ rpcauth_prune_expired(struct list_head *free, int nr_to_scan)
>  		}
>  		spin_unlock(cache_lock);
>  	}
> -	return (number_cred_unused / 100) * sysctl_vfs_cache_pressure;
> +	return number_cred_unused;
>  }
>  
>  /*
> -- 
> 1.7.6
> 
> 

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Re: [PATCH] Remove incorrect usage of sysctl_vfs_cache_pressure

[Dave Chinner]

On Mon, Jul 11, 2011 at 02:56:23AM +0530, raghu.prabhu13@gmail.com wrote:
> From: Raghavendra D Prabhu <rprabhu@wnohang.net>
> 
> In shrinker functions, sysctl_vfs_cache_pressure variable is being used while
> trimming slab caches in general and not restricted to inode/dentry caches as
> documented for that sysctl.
> 
> Raghavendra D Prabhu (1):
>   mm/vmscan: Remove sysctl_vfs_cache_pressure from non-vfs shrinkers
> 
>  drivers/gpu/drm/i915/i915_gem.c |    2 +-

That's the only questionable use of it as it has nothing to do with
filesystems.

>  fs/gfs2/glock.c                 |    2 +-
>  fs/gfs2/quota.c                 |    2 +-
>  fs/mbcache.c                    |    2 +-
>  fs/nfs/dir.c                    |    2 +-
>  fs/quota/dquot.c                |    3 +--
>  net/sunrpc/auth.c               |    2 +-

All the others are filesystema??specific caches and as such the use of
vfs_cache_pressure to adjust the balance of reclaim is valid usage.
Especially the VFS quota cache shrinkers. ;)

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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Re: [PATCH] Remove incorrect usage of sysctl_vfs_cache_pressure

[Steven Whitehouse]

Hi,

On Mon, 2011-07-11 at 12:00 +1000, Dave Chinner wrote:
> On Mon, Jul 11, 2011 at 02:56:23AM +0530, raghu.prabhu13@gmail.com wrote:
> > From: Raghavendra D Prabhu <rprabhu@wnohang.net>
> > 
> > In shrinker functions, sysctl_vfs_cache_pressure variable is being used while
> > trimming slab caches in general and not restricted to inode/dentry caches as
> > documented for that sysctl.
> > 
> > Raghavendra D Prabhu (1):
> >   mm/vmscan: Remove sysctl_vfs_cache_pressure from non-vfs shrinkers
> > 
> >  drivers/gpu/drm/i915/i915_gem.c |    2 +-
> 
> That's the only questionable use of it as it has nothing to do with
> filesystems.
> 
> >  fs/gfs2/glock.c                 |    2 +-
> >  fs/gfs2/quota.c                 |    2 +-
> >  fs/mbcache.c                    |    2 +-
> >  fs/nfs/dir.c                    |    2 +-
> >  fs/quota/dquot.c                |    3 +--
> >  net/sunrpc/auth.c               |    2 +-
> 
> All the others are filesystema??specific caches and as such the use of
> vfs_cache_pressure to adjust the balance of reclaim is valid usage.
> Especially the VFS quota cache shrinkers. ;)
> 
> Cheers,
> 
> Dave.

I agree for the two GFS2 uses of this variable. There is no need to make
this change,

Steve.


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