Messages in this thread Patch in this message | | | Date | Sat, 01 Jun 2002 01:42:02 -0700 | From | Andrew Morton <> | Subject | [patch 6/16] buffer_boundary() for ext3 |
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Implement buffer_boundary() for ext3.
buffer_boundary() is an I/O scheduling hint which the filesystem's get_block() function passes up to the BIO assembly code. It is described in fs/mpage.c
The time to read 1,000 52 kbyte files goes from 8.6 seconds down to 2.9 seconds. 52 kbytes is the worst-case size.
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--- 2.5.19/fs/ext3/inode.c~ext3-buffer_boundary Sat Jun 1 01:18:08 2002 +++ 2.5.19-akpm/fs/ext3/inode.c Sat Jun 1 01:18:08 2002 @@ -306,6 +306,8 @@ static inline int verify_chain(Indirect * @inode: inode in question (we are only interested in its superblock) * @i_block: block number to be parsed * @offsets: array to store the offsets in + * @boundary: set this non-zero if the referred-to block is likely to be + * followed (on disk) by an indirect block. * * To store the locations of file's data ext3 uses a data structure common * for UNIX filesystems - tree of pointers anchored in the inode, with @@ -330,7 +332,8 @@ static inline int verify_chain(Indirect * get there at all. */ -static int ext3_block_to_path(struct inode *inode, long i_block, int offsets[4]) +static int ext3_block_to_path(struct inode *inode, + long i_block, int offsets[4], int *boundary) { int ptrs = EXT3_ADDR_PER_BLOCK(inode->i_sb); int ptrs_bits = EXT3_ADDR_PER_BLOCK_BITS(inode->i_sb); @@ -338,26 +341,33 @@ static int ext3_block_to_path(struct ino indirect_blocks = ptrs, double_blocks = (1 << (ptrs_bits * 2)); int n = 0; + int final = 0; if (i_block < 0) { ext3_warning (inode->i_sb, "ext3_block_to_path", "block < 0"); } else if (i_block < direct_blocks) { offsets[n++] = i_block; + final = direct_blocks; } else if ( (i_block -= direct_blocks) < indirect_blocks) { offsets[n++] = EXT3_IND_BLOCK; offsets[n++] = i_block; + final = ptrs; } else if ((i_block -= indirect_blocks) < double_blocks) { offsets[n++] = EXT3_DIND_BLOCK; offsets[n++] = i_block >> ptrs_bits; offsets[n++] = i_block & (ptrs - 1); + final = ptrs; } else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) { offsets[n++] = EXT3_TIND_BLOCK; offsets[n++] = i_block >> (ptrs_bits * 2); offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1); offsets[n++] = i_block & (ptrs - 1); + final = ptrs; } else { ext3_warning (inode->i_sb, "ext3_block_to_path", "block > big"); } + if (boundary) + *boundary = (i_block & (ptrs - 1)) == (final - 1); return n; } @@ -734,7 +744,8 @@ static int ext3_get_block_handle(handle_ Indirect *partial; unsigned long goal; int left; - int depth = ext3_block_to_path(inode, iblock, offsets); + int boundary = 0; + int depth = ext3_block_to_path(inode, iblock, offsets, &boundary); struct ext3_inode_info *ei = EXT3_I(inode); loff_t new_size; @@ -752,6 +763,8 @@ reread: clear_buffer_new(bh_result); got_it: map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key)); + if (boundary) + set_buffer_boundary(bh_result); /* Clean up and exit */ partial = chain+depth-1; /* the whole chain */ goto cleanup; @@ -1875,7 +1888,7 @@ void ext3_truncate(struct inode * inode) ext3_block_truncate_page(handle, inode->i_mapping, inode->i_size); - n = ext3_block_to_path(inode, last_block, offsets); + n = ext3_block_to_path(inode, last_block, offsets, NULL); if (n == 0) goto out_stop; /* error */ - - 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/
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