lkml.org 
[lkml]   [2010]   [May]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4/5] superblock: add filesystem shrinker operations
    Date
    From: Dave Chinner <dchinner@redhat.com>

    Now we have a per-superblock shrinker implementation, we can add a
    filesystem specific callout to it to allow filesystem internal
    caches to be shrunk by the superblock shrinker.

    Rather than perpetuate the multipurpose shrinker callback API (i.e.
    nr_to_scan == 0 meaning "tell me how many objects freeable in the
    cache), two operations will be added. The first will return the
    number of objects that are freeable, the second is the actual
    shrinker call.

    Signed-off-by: Dave Chinner <dchinner@redhat.com>
    ---
    fs/super.c | 43 +++++++++++++++++++++++++++++++------------
    include/linux/fs.h | 11 +++++++++++
    2 files changed, 42 insertions(+), 12 deletions(-)

    diff --git a/fs/super.c b/fs/super.c
    index 339b590..e98292e 100644
    --- a/fs/super.c
    +++ b/fs/super.c
    @@ -48,7 +48,8 @@ DEFINE_SPINLOCK(sb_lock);
    static int prune_super(struct shrinker *shrink, int nr_to_scan, gfp_t gfp_mask)
    {
    struct super_block *sb;
    - int count;
    + int fs_objects = 0;
    + int total_objects;

    sb = container_of(shrink, struct super_block, s_shrink);

    @@ -71,22 +72,40 @@ static int prune_super(struct shrinker *shrink, int nr_to_scan, gfp_t gfp_mask)
    return -1;
    }

    - if (nr_to_scan) {
    - /* proportion the scan between the two cacheѕ */
    - int total;
    -
    - total = sb->s_nr_dentry_unused + sb->s_nr_inodes_unused + 1;
    - count = (nr_to_scan * sb->s_nr_dentry_unused) / total;
    + if (sb->s_op && sb->s_op->nr_cached_objects)
    + fs_objects = sb->s_op->nr_cached_objects(sb);

    - /* prune dcache first as icache is pinned by it */
    - prune_dcache_sb(sb, count);
    - prune_icache_sb(sb, nr_to_scan - count);
    + total_objects = sb->s_nr_dentry_unused +
    + sb->s_nr_inodes_unused + fs_objects + 1;
    + if (nr_to_scan) {
    + int dentries;
    + int inodes;
    +
    + /* proportion the scan between the cacheѕ */
    + dentries = (nr_to_scan * sb->s_nr_dentry_unused) /
    + total_objects;
    + inodes = (nr_to_scan * sb->s_nr_inodes_unused) /
    + total_objects;
    + if (fs_objects)
    + fs_objects = (nr_to_scan * fs_objects) /
    + total_objects;
    + /*
    + * prune the dcache first as the icache is pinned by it, then
    + * prune the icache, followed by the filesystem specific caches
    + */
    + prune_dcache_sb(sb, dentries);
    + prune_icache_sb(sb, inodes);
    + if (sb->s_op && sb->s_op->free_cached_objects) {
    + sb->s_op->free_cached_objects(sb, fs_objects);
    + fs_objects = sb->s_op->nr_cached_objects(sb);
    + }
    + total_objects = sb->s_nr_dentry_unused +
    + sb->s_nr_inodes_unused + fs_objects;
    }

    - count = ((sb->s_nr_dentry_unused + sb->s_nr_inodes_unused) / 100)
    - * sysctl_vfs_cache_pressure;
    + total_objects = (total_objects / 100) * sysctl_vfs_cache_pressure;
    up_read(&sb->s_umount);
    - return count;
    + return total_objects;
    }

    /**
    diff --git a/include/linux/fs.h b/include/linux/fs.h
    index 6ba3739..ef2e9e2 100644
    --- a/include/linux/fs.h
    +++ b/include/linux/fs.h
    @@ -1591,6 +1591,17 @@ struct super_operations {
    ssize_t (*quota_write)(struct super_block *, int, const char *, size_t, loff_t);
    #endif
    int (*bdev_try_to_free_page)(struct super_block*, struct page*, gfp_t);
    +
    + /*
    + * memory shrinker operations.
    + * ->nr_cached_objects() should return the number of freeable cached
    + * objects the filesystem holds.
    + * ->free_cache_objects() should attempt to free the number of cached
    + * objects indicated. It should return how many objects it attempted to
    + * free.
    + */
    + int (*nr_cached_objects)(struct super_block *);
    + int (*free_cached_objects)(struct super_block *, int);
    };

    /*
    --
    1.5.6.5
    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2010-05-14 09:27    [W:0.039 / U:121.320 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site