From 275f495dbe34300d793466a7d96c70f83fbae1bc Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Thu, 4 Jul 2013 19:04:01 +0200 Subject: [PATCH] hpfs: implement prefetch to improve performance This patch implements prefetch to improve performance. It helps mostly when scanning the bitmaps to calculate free space. Signed-off-by: Mikulas Patocka Signed-off-by: Linus Torvalds --- fs/hpfs/buffer.c | 33 +++++++++++++++++++++++++++++++++ fs/hpfs/hpfs_fn.h | 7 +++++-- fs/hpfs/map.c | 19 ++++++++++++++++++- fs/hpfs/super.c | 9 +++++++-- 4 files changed, 63 insertions(+), 5 deletions(-) diff --git a/fs/hpfs/buffer.c b/fs/hpfs/buffer.c index f49d149..4d0a1af 100644 --- a/fs/hpfs/buffer.c +++ b/fs/hpfs/buffer.c @@ -7,8 +7,37 @@ */ #include #include +#include #include "hpfs_fn.h" +void hpfs_prefetch_sectors(struct super_block *s, unsigned secno, int n) +{ + struct buffer_head *bh; + struct blk_plug plug; + + if (n <= 0 || unlikely(secno >= hpfs_sb(s)->sb_fs_size)) + return; + + bh = sb_find_get_block(s, secno); + if (bh) { + if (buffer_uptodate(bh)) { + brelse(bh); + return; + } + brelse(bh); + }; + + blk_start_plug(&plug); + while (n > 0) { + if (unlikely(secno >= hpfs_sb(s)->sb_fs_size)) + break; + sb_breadahead(s, secno); + secno++; + n--; + } + blk_finish_plug(&plug); +} + /* Map a sector into a buffer and return pointers to it and to the buffer. */ void *hpfs_map_sector(struct super_block *s, unsigned secno, struct buffer_head **bhp, @@ -18,6 +47,8 @@ void *hpfs_map_sector(struct super_block *s, unsigned secno, struct buffer_head hpfs_lock_assert(s); + hpfs_prefetch_sectors(s, secno, ahead); + cond_resched(); *bhp = bh = sb_bread(s, secno); @@ -67,6 +98,8 @@ void *hpfs_map_4sectors(struct super_block *s, unsigned secno, struct quad_buffe return NULL; } + hpfs_prefetch_sectors(s, secno, 4 + ahead); + qbh->data = data = kmalloc(2048, GFP_NOFS); if (!data) { printk("HPFS: hpfs_map_4sectors: out of memory\n"); diff --git a/fs/hpfs/hpfs_fn.h b/fs/hpfs/hpfs_fn.h index b7ae286..1b39863 100644 --- a/fs/hpfs/hpfs_fn.h +++ b/fs/hpfs/hpfs_fn.h @@ -27,8 +27,9 @@ #define ALLOC_FWD_MAX 128 #define ALLOC_M 1 #define FNODE_RD_AHEAD 16 -#define ANODE_RD_AHEAD 16 -#define DNODE_RD_AHEAD 4 +#define ANODE_RD_AHEAD 0 +#define DNODE_RD_AHEAD 72 +#define COUNT_RD_AHEAD 62 #define FREE_DNODES_ADD 58 #define FREE_DNODES_DEL 29 @@ -207,6 +208,7 @@ void hpfs_remove_fnode(struct super_block *, fnode_secno fno); /* buffer.c */ +void hpfs_prefetch_sectors(struct super_block *, unsigned, int); void *hpfs_map_sector(struct super_block *, unsigned, struct buffer_head **, int); void *hpfs_get_sector(struct super_block *, unsigned, struct buffer_head **); void *hpfs_map_4sectors(struct super_block *, unsigned, struct quad_buffer_head *, int); @@ -271,6 +273,7 @@ void hpfs_evict_inode(struct inode *); __le32 *hpfs_map_dnode_bitmap(struct super_block *, struct quad_buffer_head *); __le32 *hpfs_map_bitmap(struct super_block *, unsigned, struct quad_buffer_head *, char *); +void hpfs_prefetch_bitmap(struct super_block *, unsigned); unsigned char *hpfs_load_code_page(struct super_block *, secno); __le32 *hpfs_load_bitmap_directory(struct super_block *, secno bmp); struct fnode *hpfs_map_fnode(struct super_block *s, ino_t, struct buffer_head **); diff --git a/fs/hpfs/map.c b/fs/hpfs/map.c index 803d3da..3aa66ae 100644 --- a/fs/hpfs/map.c +++ b/fs/hpfs/map.c @@ -17,6 +17,7 @@ __le32 *hpfs_map_bitmap(struct super_block *s, unsigned bmp_block, struct quad_buffer_head *qbh, char *id) { secno sec; + __le32 *ret; unsigned n_bands = (hpfs_sb(s)->sb_fs_size + 0x3fff) >> 14; if (hpfs_sb(s)->sb_chk) if (bmp_block >= n_bands) { hpfs_error(s, "hpfs_map_bitmap called with bad parameter: %08x at %s", bmp_block, id); @@ -27,7 +28,23 @@ __le32 *hpfs_map_bitmap(struct super_block *s, unsigned bmp_block, hpfs_error(s, "invalid bitmap block pointer %08x -> %08x at %s", bmp_block, sec, id); return NULL; } - return hpfs_map_4sectors(s, sec, qbh, 4); + ret = hpfs_map_4sectors(s, sec, qbh, 4); + if (ret) hpfs_prefetch_bitmap(s, bmp_block + 1); + return ret; +} + +void hpfs_prefetch_bitmap(struct super_block *s, unsigned bmp_block) +{ + unsigned to_prefetch, next_prefetch; + unsigned n_bands = (hpfs_sb(s)->sb_fs_size + 0x3fff) >> 14; + if (unlikely(bmp_block >= n_bands)) + return; + to_prefetch = le32_to_cpu(hpfs_sb(s)->sb_bmp_dir[bmp_block]); + if (unlikely(bmp_block + 1 >= n_bands)) + next_prefetch = 0; + else + next_prefetch = le32_to_cpu(hpfs_sb(s)->sb_bmp_dir[bmp_block + 1]); + hpfs_prefetch_sectors(s, to_prefetch, 4 + 4 * (to_prefetch + 4 == next_prefetch)); } /* diff --git a/fs/hpfs/super.c b/fs/hpfs/super.c index 962e90c..4334cda 100644 --- a/fs/hpfs/super.c +++ b/fs/hpfs/super.c @@ -121,7 +121,7 @@ unsigned hpfs_count_one_bitmap(struct super_block *s, secno secno) unsigned long *bits; unsigned count; - bits = hpfs_map_4sectors(s, secno, &qbh, 4); + bits = hpfs_map_4sectors(s, secno, &qbh, 0); if (!bits) return 0; count = bitmap_weight(bits, 2048 * BITS_PER_BYTE); @@ -134,8 +134,13 @@ static unsigned count_bitmaps(struct super_block *s) unsigned n, count, n_bands; n_bands = (hpfs_sb(s)->sb_fs_size + 0x3fff) >> 14; count = 0; - for (n = 0; n < n_bands; n++) + for (n = 0; n < COUNT_RD_AHEAD; n++) { + hpfs_prefetch_bitmap(s, n); + } + for (n = 0; n < n_bands; n++) { + hpfs_prefetch_bitmap(s, n + COUNT_RD_AHEAD); count += hpfs_count_one_bitmap(s, le32_to_cpu(hpfs_sb(s)->sb_bmp_dir[n])); + } return count; } -- 2.7.4