Re: [PATCH 2/4] ext2fs: improve diskfs_node_iterate

[Samuel Thibault]

Justus Winter, le Wed 30 Apr 2014 11:06:00 +0200, a écrit :
> Currently, diskfs_node_iterate iterates twice over all nodes in the
> cache.  The first time only to determine the number of nodes currently
> in the cache.  Simply count them instead.

Ack.

> * ext2fs/inode.c (nodehash_nr_items): New variable.
> (diskfs_cached_lookup): Increment nodehash_nr_items.
> (diskfs_node_norefs): Decrement nodehash_nr_items.
> (diskfs_node_iterate): Fix the type of num_nodes, use nodehash_nr_items.
> ---
>  ext2fs/inode.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/ext2fs/inode.c b/ext2fs/inode.c
> index e75c63f..ed78265 100644
> --- a/ext2fs/inode.c
> +++ b/ext2fs/inode.c
> @@ -47,6 +47,7 @@
>  #endif
>  
>  static struct node *nodehash[INOHSZ];
> +static size_t nodehash_nr_items;
>  
>  static error_t read_node (struct node *np);
>  
> @@ -106,6 +107,7 @@ diskfs_cached_lookup (ino_t inum, struct node **npp)
>      dn->hnext->dn->hprevp = &dn->hnext;
>    dn->hprevp = &nodehash[INOHASH(inum)];
>    nodehash[INOHASH(inum)] = np;
> +  nodehash_nr_items += 1;
>  
>    pthread_spin_unlock (&diskfs_node_refcnt_lock);
>  
> @@ -159,6 +161,7 @@ diskfs_node_norefs (struct node *np)
>    *np->dn->hprevp = np->dn->hnext;
>    if (np->dn->hnext)
>      np->dn->hnext->dn->hprevp = np->dn->hprevp;
> +  nodehash_nr_items -= 1;
>  
>    if (np->dn->dirents)
>      free (np->dn->dirents);
> @@ -549,7 +552,8 @@ error_t
>  diskfs_node_iterate (error_t (*fun)(struct node *))
>  {
>    error_t err = 0;
> -  int n, num_nodes = 0;
> +  int n;
> +  size_t num_nodes;
>    struct node *node, **node_list, **p;
>  
>    pthread_spin_lock (&diskfs_node_refcnt_lock);
> @@ -559,10 +563,7 @@ diskfs_node_iterate (error_t (*fun)(struct node *))
>       during processing (normally we delegate access to hash-table with
>       diskfs_node_refcnt_lock, but we can't hold this while locking the
>       individual node locks).  */
> -
> -  for (n = 0; n < INOHSZ; n++)
> -    for (node = nodehash[n]; node; node = node->dn->hnext)
> -      num_nodes++;
> +  num_nodes = nodehash_nr_items;
>  
>    /* TODO This method doesn't scale beyond a few dozen nodes and should be
>       replaced.  */
> -- 
> 1.9.2
> 

-- 
Samuel
 CN > J'ai enseigné l'algorythmique.
 GLG> C'est quoi l'algorythmique ? Une contrebasse programmée en Algol ?
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