On Tue, Dec 23, 2008 at 9:59 AM, Peter Teoh <htmldeveloper@xxxxxxxxx> wrote:
> Sorry, resent due to SMTP error:
>
> anyone knows any way of enumerating all the low level information like
> these for each file?
>
> Best I can get is "debugfs":
>
> So using "show_inode_infor xxxx":
>
> Inode: 1146884 Type: regular Mode: 0767 Flags: 0x0
> Generation: 4262211373
> User: 0 Group: 0 Size: 4670783
> File ACL: 0 Directory ACL: 0
> Links: 1 Blockcount: 9152
> Fragment: Address: 0 Number: 0 Size: 0
> ctime: 0x46db7fb6 -- Mon Sep 3 11:29:58 2007
> atime: 0x47c66735 -- Thu Feb 28 15:48:05 2008
> mtime: 0x43118298 -- Sun Aug 28 17:23:36 2005
> BLOCKS:
> (0-11):2317946-0, (IND):2317958, (12-1035):2317959-0, (DIND):2318983,
> (IND):2318984, (1036-1140):2318985-0
> TOTAL: 1144
>
> Here the "BLOCKS" correspond to the block numbering we are talking
> about, right? It always start at 0 per-file. "IND" is the indirect
> block.
> But what is "DIND"?
Double indirect blocks ..... Sine the size of file is 4670783, we
would need 1140 direct blocks (holding data) and other indirect
blocks.
> "2317946" is the physical block number
> right?
Yes.......
> And what is the zero after the "2317946"?
0 is just the end specifier for a range which debugfs prints. So
either you print the range of blocks or a 0 at the end to mark the
start of a new range. The code to do is present in
e2fsprogs/debugfs/debugfs.c : list_blocks_proc()
list_block_proc () {
...................
/*
* Not a normal block. Always force a new range.
*/
finish_range(lb);
if (lb->first)
lb->first = 0;
else
fprintf(lb->f, ", ");
if (blockcnt == -1)
fprintf(lb->f, "(IND):%u", *blocknr);
else if (blockcnt == -2)
fprintf(lb->f, "(DIND):%u", *blocknr);
else if (blockcnt == -3)
fprintf(lb->f, "(TIND):%u", *blocknr);
...................
}
Thanks -
Manish
>
> On Tue, Dec 23, 2008 at 10:56 AM, Mike Snitzer <snitzer@xxxxxxxxx> wrote:
>>
>> On Sat, Dec 20, 2008 at 8:25 PM, Peter Teoh <htmldeveloper@xxxxxxxxx> wrote:
>> > On Sat, Dec 20, 2008 at 11:43 PM, Rohit Sharma <imreckless@xxxxxxxxx> wrote:
>> >> A little confusion.
>> >>
>> >> Just refer this structure in linux/ext2_fs_sb.h
>> >>
>> >> struct ext2_block_alloc_info {
>> >> 46 /* information about reservation window */
>> >> 47 struct ext2_reserve_window_node rsv_window_node;
>> >> 48 /*
>> >> 49 * was i_next_alloc_block in ext2_inode_info
>> >> 50 * is the logical (file-relative) number of the
>> >> 51 * most-recently-allocated block in this file.
>> >> 52 * We use this for detecting linearly ascending allocation requests.
>> >> 53 */
>> >> 54 __u32 last_alloc_logical_block;
>> >
>> > if i interpret the meaning of "file-relative logical number"
>> > correctly, and since one-file-one-inode concept, then it means that it
>> > should mean inode-relative logical block number.
>> >
>> >> 55 /*
>> >> 56 * Was i_next_alloc_goal in ext2_inode_info
>> >> 57 * is the *physical* companion to i_next_alloc_block.
>> >> 58 * it the the physical block number of the block which was
>> >
>> >> inode1 has logical blocks 0 1 2 , physical 22 23 24
>> >> inode2 has logical blocks 0 1 2 , physical 34 35 50
>> >>
>> >
>> > as per comment above, the sequence above looks likely, but then this
>> > is my guess again.
>>
>> You are correct. last_alloc_logical_block is used to detect if the
>> write workload against a given inode is sequential (the current
>> logical block is last_alloc_logical_block+1).
>>
>> Mike
>
>
>
> --
> Regards,
> Peter Teoh
>
> Ernest Hemingway - "Never mistake motion for action."
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