On Thu, Mar 12, 2009 at 9:43 PM, Greg Freemyer <greg.freemyer@xxxxxxxxx> wrote: > On Thu, Mar 12, 2009 at 11:16 AM, Sandeep K Sinha > <sandeepksinha@xxxxxxxxx> wrote: >> Hi all, >> >> I am listing above two codes for re-allocating new blocks for a given inode. >> >> These code snippets are specific to ext2. >> The problem here is that it is performing slower than cp and dd. >> >> Can anyone help in determining what can be the possible reason(s) ? > > Excessive use of sync_dirty_buffer(); > > You're calling it for every single block you copy. Pretty sure it is a > very aggressive call that forces the data out to the disk immediately, > thus the benefits of caching and elevators are lost. And those are > big benefits. > probably the reason being that the ext2 has some issues with sync. http://kerneltrap.org/index.php?q=mailarchive/linux-fsdevel/2007/2/14/316836/thread Hence, if we don't do this we see a difference in the original and reallocated file. > Greg > > >> >> 1. MEMCPY >> ======= >> >> >> >> src_ind = ext2_iget (sb, inum); >> if (!src_ind) { >> printk (KERN_DEBUG "\n OHSM Source Inode Not Found "); >> goto out_err; >> } >> >> /* Getting the ghost inode */ >> dest_ind = ext2_new_inode (nd.path.dentry->d_inode, src_ind->i_mode); >> if (IS_ERR(dest_ind)) { >> printk (KERN_ALERT "\n OHSM destination inode unable to allocate. >> err = %ld", PTR_ERR(dest_ind)); >> goto out_err; >> } >> >> /* Locking the source inode using mutex */ >> mutex_lock (&src_ind->i_mutex); >> >> /* Get the source inode size and number of blocks */ >> i_size = i_size_read(src_ind); >> >> /* Calculating number of block to allocate for ghost inode */ >> nblocks = (i_size >> EXT2_BLOCK_SIZE_BITS(sb)) + >> ((i_size & (sb->s_blocksize - 1)) ? 1 : 0); >> >> memset(&dest_bh, 0, sizeof(struct buffer_head)); >> memset(&src_bh, 0, sizeof(struct buffer_head)); >> for (done = 0; done < nblocks; done++) { >> >> err = ext2_get_block (src_ind, done, &src_bh, 0); >> if (err < 0) { >> printk (KERN_DEBUG "\n error getting blocks ret_val = %d",err); >> goto unlock; >> } >> >> dest_bh.b_state = 0; >> err = ext2_get_block (dest_ind, done, &dest_bh, 1); >> if (err < 0) { >> printk (KERN_DEBUG "\n error getting blocks ret_val = %d",err); >> goto unlock; >> } >> >> if (!buffer_mapped(&src_bh)){ >> printk (KERN_DEBUG "\nHOLE "); >> continue; >> } >> >> src_bhptr = sb_bread(sb, src_bh.b_blocknr); >> if (!src_bhptr) >> goto unlock; >> >> dst_bhptr = sb_bread(sb, dest_bh.b_blocknr); >> if (!dst_bhptr) >> goto unlock; >> >> lock_buffer(dst_bhptr); >> memcpy(dst_bhptr->b_data,src_bhptr->b_data,src_bhptr->b_size); >> unlock_buffer(dst_bhptr); >> >> mark_buffer_dirty(dst_bhptr); >> sync_dirty_buffer(dst_bhptr); >> >> brelse(src_bhptr); >> brelse(dst_bhptr); >> >> } >> >> for (blk_index = 0; blk_index < 15; blk_index++) { >> if (EXT2_I (dest_ind)->i_data[blk_index]){ >> swap = EXT2_I (src_ind)->i_data[blk_index]; >> EXT2_I (src_ind)->i_data[blk_index] = >> EXT2_I (dest_ind)->i_data[blk_index]; >> EXT2_I (dest_ind)->i_data[blk_index] = swap; >> } >> } >> >> dest_ind->i_blocks = src_ind->i_blocks ; >> mark_inode_dirty (src_ind); >> sync_mapping_buffers(src_ind->i_mapping); >> ohsm_sync_inode(src_ind); >> iput(src_ind); >> >> dest_ind->i_nlink = 0; >> iput(dest_ind); >> mutex_unlock (&src_ind->i_mutex); >> goto out_err; >> >> unlock: >> brelse(src_bhptr); >> brelse(dst_bhptr); >> mutex_unlock (&src_ind->i_mutex); >> >> out_err: >> path_put (&nd.path); >> return; >> >> >> >> 2. PAGEFLIP >> ======== >> >> >> /* Get the source inode */ >> >> src_ind = ext2_iget (sb, inum); >> if (!src_ind) { >> printk (KERN_DEBUG "\n OHSM Source Inode Not Found "); >> goto out_err; >> } >> >> /* Getting the ghost inode */ >> dest_ind = ext2_new_inode (nd.path.dentry->d_inode, src_ind->i_mode); >> if (IS_ERR(dest_ind)) { >> printk (KERN_ALERT "\n destination inode unable to allocate. err = >> %ld", PTR_ERR(dest_ind)); >> goto out_err; >> } >> >> /* Locking the source inode using mutex */ >> mutex_lock (&src_ind->i_mutex); >> >> /* Get the source inode size and number of blocks */ >> i_size = i_size_read(src_ind); >> >> /* Calculating number of block to allocate for ghost inode */ >> nblocks = (i_size >> EXT2_BLOCK_SIZE_BITS(sb)) + >> ((i_size & (sb->s_blocksize - 1)) ? 1 : 0); >> >> >> memset(&dest_bh, 0, sizeof(struct buffer_head)); >> memset(&src_bh, 0, sizeof(struct buffer_head)); >> for (done = 0; done < nblocks; done++) { >> >> err = ext2_get_block (src_ind, done, &src_bh, 0); >> if (err < 0) { >> printk (KERN_DEBUG "\n error getting blocks ret_val = %d",err); >> goto unlock; >> } >> >> dest_bh.b_state = 0; >> err = ext2_get_block (dest_ind, done, &dest_bh, 1); >> if (err < 0) { >> printk (KERN_DEBUG "\n error getting blocks ret_val = %d",err); >> goto unlock; >> } >> >> if (!buffer_mapped(&src_bh)){ >> printk (KERN_DEBUG "\nHOLE "); >> continue; >> } >> >> src_bhptr = sb_bread(sb, src_bh.b_blocknr); >> if (!src_bhptr) >> goto unlock; >> >> dst_bhptr = sb_bread(sb, dest_bh.b_blocknr); >> if (!dst_bhptr) >> goto unlock; >> >> lock_buffer(dst_bhptr); >> oldpage = dst_bhptr->b_page; >> olddata = dst_bhptr->b_data; >> dst_bhptr->b_data = src_bhptr->b_data; >> dst_bhptr->b_page = src_bhptr->b_page; >> flush_dcache_page(dst_bhptr->b_page); >> unlock_buffer(dst_bhptr); >> >> mark_buffer_dirty(dst_bhptr); >> sync_dirty_buffer(dst_bhptr); >> >> if(buffer_uptodate(dst_bhptr)) { >> dst_bhptr->b_page = oldpage; >> dst_bhptr->b_data = olddata; >> } >> >> brelse(src_bhptr); >> brelse(dst_bhptr); >> } >> >> for (blk_index = 0; blk_index < 15; blk_index++) { >> if (EXT2_I (dest_ind)->i_data[blk_index]){ >> swap = EXT2_I (src_ind)->i_data[blk_index]; >> EXT2_I (src_ind)->i_data[blk_index] = >> EXT2_I (dest_ind)->i_data[blk_index]; >> EXT2_I (dest_ind)->i_data[blk_index] = swap; >> } >> } >> >> dest_ind->i_blocks = src_ind->i_blocks ; >> mark_inode_dirty (src_ind); >> sync_mapping_buffers(src_ind->i_mapping); >> ohsm_sync_inode(src_ind); >> iput(src_ind); >> >> dest_ind->i_nlink = 0; >> iput(dest_ind); >> mutex_unlock (&src_ind->i_mutex); >> goto out_err; >> >> unlock: >> brelse(src_bhptr); >> brelse(dst_bhptr); >> mutex_unlock (&src_ind->i_mutex); >> >> out_err: >> path_put (&nd.path); >> return; >> } >> >> >> >> -- >> Regards, >> Sandeep. >> >> >> >> >> >> >> “To learn is to change. Education is a process that changes the learner.” >> > > > > -- > Greg Freemyer > Litigation Triage Solutions Specialist > http://www.linkedin.com/in/gregfreemyer > First 99 Days Litigation White Paper - > http://www.norcrossgroup.com/forms/whitepapers/99%20Days%20whitepaper.pdf > > The Norcross Group > The Intersection of Evidence & Technology > http://www.norcrossgroup.com > -- Regards, Sandeep. “To learn is to change. Education is a process that changes the learner.” -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
