On Thu, Feb 07, 2013 at 03:38:34PM -0600, Mitch Harder wrote:
> Provide for modification of the limit of compressed extent size
> utilizing mount-time configuration settings.
>
> The size of compressed extents was limited to 128K, which
> leads to fragmentation of the extents (although the extents
> themselves may still be located contiguously). This limit is
> put in place to ease the RAM required when spreading compression
> across several CPUs, and to make sure the amount of IO required
> to do a random read is reasonably small.
>
> Signed-off-by: Mitch Harder <mitch.harder@xxxxxxxxxxxxxxxx>
> ---
> Changelog v1 -> v2:
> - Use more self-documenting variable name:
> compressed_extent_size -> max_compressed_extent_kb
> - Use #define BTRFS_DEFAULT_MAX_COMPR_EXTENTS instead of raw 128.
> - Fix min calculation for nr_pages.
> - Comment cleanup.
> - Use more self-documenting mount option parameter:
> compressed_extent_size -> max_compressed_extent_kb
> - Fix formatting in btrfs_show_options.
> ---
> fs/btrfs/ctree.h | 6 ++++++
> fs/btrfs/disk-io.c | 1 +
> fs/btrfs/inode.c | 8 ++++----
> fs/btrfs/relocation.c | 7 ++++---
> fs/btrfs/super.c | 20 +++++++++++++++++++-
> 5 files changed, 34 insertions(+), 8 deletions(-)
>
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 547b7b0..a62f20c 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -191,6 +191,9 @@ static int btrfs_csum_sizes[] = { 4, 0 };
> /* ioprio of readahead is set to idle */
> #define BTRFS_IOPRIO_READA (IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0))
>
> +/* Default value for maximum compressed extent size (kb) */
> +#define BTRFS_DEFAULT_MAX_COMPR_EXTENTS 128
> +
> /*
> * The key defines the order in the tree, and so it also defines (optimal)
> * block layout.
> @@ -1477,6 +1480,8 @@ struct btrfs_fs_info {
> unsigned data_chunk_allocations;
> unsigned metadata_ratio;
>
> + unsigned max_compressed_extent_kb;
> +
> void *bdev_holder;
>
> /* private scrub information */
> @@ -1829,6 +1834,7 @@ struct btrfs_ioctl_defrag_range_args {
> #define BTRFS_MOUNT_CHECK_INTEGRITY (1 << 20)
> #define BTRFS_MOUNT_CHECK_INTEGRITY_INCLUDING_EXTENT_DATA (1 << 21)
> #define BTRFS_MOUNT_PANIC_ON_FATAL_ERROR (1 << 22)
> +#define BTRFS_MOUNT_COMPR_EXTENT_SIZE (1 << 23)
>
> #define btrfs_clear_opt(o, opt) ((o) &= ~BTRFS_MOUNT_##opt)
> #define btrfs_set_opt(o, opt) ((o) |= BTRFS_MOUNT_##opt)
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index 830bc17..775e7ba 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -2056,6 +2056,7 @@ int open_ctree(struct super_block *sb,
> fs_info->trans_no_join = 0;
> fs_info->free_chunk_space = 0;
> fs_info->tree_mod_log = RB_ROOT;
> + fs_info->max_compressed_extent_kb = BTRFS_DEFAULT_MAX_COMPR_EXTENTS;
>
> /* readahead state */
> INIT_RADIX_TREE(&fs_info->reada_tree, GFP_NOFS & ~__GFP_WAIT);
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 148abeb..78fc6eb 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -346,8 +346,8 @@ static noinline int compress_file_range(struct inode *inode,
> unsigned long nr_pages_ret = 0;
> unsigned long total_compressed = 0;
> unsigned long total_in = 0;
> - unsigned long max_compressed = 128 * 1024;
> - unsigned long max_uncompressed = 128 * 1024;
> + unsigned long max_compressed = root->fs_info->max_compressed_extent_kb * 1024;
> + unsigned long max_uncompressed = root->fs_info->max_compressed_extent_kb * 1024;
> int i;
> int will_compress;
> int compress_type = root->fs_info->compress_type;
> @@ -361,7 +361,7 @@ static noinline int compress_file_range(struct inode *inode,
> again:
> will_compress = 0;
> nr_pages = (end >> PAGE_CACHE_SHIFT) - (start >> PAGE_CACHE_SHIFT) + 1;
> - nr_pages = min(nr_pages, (128 * 1024UL) / PAGE_CACHE_SIZE);
> + nr_pages = min(nr_pages, max_compressed / PAGE_CACHE_SIZE);
>
> /*
> * we don't want to send crud past the end of i_size through
> @@ -386,7 +386,7 @@ again:
> *
> * We also want to make sure the amount of IO required to do
> * a random read is reasonably small, so we limit the size of
> - * a compressed extent to 128k.
> + * a compressed extent.
> */
> total_compressed = min(total_compressed, max_uncompressed);
> num_bytes = (end - start + blocksize) & ~(blocksize - 1);
> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
> index 300e09a..64bbc9e 100644
> --- a/fs/btrfs/relocation.c
> +++ b/fs/btrfs/relocation.c
> @@ -144,7 +144,7 @@ struct tree_block {
> unsigned int key_ready:1;
> };
>
> -#define MAX_EXTENTS 128
> +#define MAX_EXTENTS 512
>
> struct file_extent_cluster {
> u64 start;
> @@ -3055,6 +3055,7 @@ int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
> struct file_extent_cluster *cluster)
> {
> int ret;
> + struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
>
> if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {
> ret = relocate_file_extent_cluster(inode, cluster);
> @@ -3066,12 +3067,12 @@ int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
> if (!cluster->nr)
> cluster->start = extent_key->objectid;
> else
> - BUG_ON(cluster->nr >= MAX_EXTENTS);
> + BUG_ON(cluster->nr >= fs_info->max_compressed_extent_kb);
> cluster->end = extent_key->objectid + extent_key->offset - 1;
> cluster->boundary[cluster->nr] = extent_key->objectid;
> cluster->nr++;
>
> - if (cluster->nr >= MAX_EXTENTS) {
> + if (cluster->nr >= fs_info->max_compressed_extent_kb) {
> ret = relocate_file_extent_cluster(inode, cluster);
> if (ret)
> return ret;
MAX_EXTENTS is irrelevant to compress, it's just for efficiency of relocation.
thanks,
liubo
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index d8982e9..25b8dc2 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -322,7 +322,7 @@ enum {
> Opt_no_space_cache, Opt_recovery, Opt_skip_balance,
> Opt_check_integrity, Opt_check_integrity_including_extent_data,
> Opt_check_integrity_print_mask, Opt_fatal_errors,
> - Opt_err,
> + Opt_max_compr_extent_kb, Opt_err,
> };
>
> static match_table_t tokens = {
> @@ -361,6 +361,7 @@ static match_table_t tokens = {
> {Opt_check_integrity, "check_int"},
> {Opt_check_integrity_including_extent_data, "check_int_data"},
> {Opt_check_integrity_print_mask, "check_int_print_mask=%d"},
> + {Opt_max_compr_extent_kb, "max_compressed_extent_kb=%d"},
> {Opt_fatal_errors, "fatal_errors=%s"},
> {Opt_err, NULL},
> };
> @@ -612,6 +613,20 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
> ret = -EINVAL;
> goto out;
> #endif
> + case Opt_max_compr_extent_kb:
> + intarg = 0;
> + match_int(&args[0], &intarg);
> + if ((intarg == 128) || (intarg == 512)) {
> + info->max_compressed_extent_kb = intarg;
> + printk(KERN_INFO "btrfs: "
> + "max compressed extent size %d KB\n",
> + info->max_compressed_extent_kb);
> + } else {
> + printk(KERN_INFO "btrfs: "
> + "Invalid compressed extent size,"
> + " using default.\n");
> + }
> + break;
> case Opt_fatal_errors:
> if (strcmp(args[0].from, "panic") == 0)
> btrfs_set_opt(info->mount_opt,
> @@ -951,6 +966,9 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
> seq_puts(seq, ",skip_balance");
> if (btrfs_test_opt(root, PANIC_ON_FATAL_ERROR))
> seq_puts(seq, ",fatal_errors=panic");
> + if (btrfs_test_opt(root, COMPR_EXTENT_SIZE))
> + seq_printf(seq, ",max_compressed_extent_kb=%u",
> + info->max_compressed_extent_kb);
> return 0;
> }
>
> --
> 1.7.12.4
>
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