On Tue, Apr 29, 2008 at 03:19:35PM -0500, Eric Sandeen wrote: > Aneesh Kumar K.V wrote: > > Hi Eric, > > > > I haven't yet tested this. Let me know what you think. > > > > -aneesh > > I'll look over it when I get a chance; I did do a quick test with my RM > scenario, and it came in about 1s faster than stock (5s vs. 6s) :) > > http://people.redhat.com/esandeen/rm_test/ext4_aneesh_rm.png I did minimal testing. The layout of the meta-data blocks using the patch is marked below. So the patch actually cluster the meta-data blocks together. In the patch I am preallocating some blocks which are used for the subsequent meta-block request. Number of blocks preallocated is determined by static void ext4_mb_normalize_meta_data_request(struct ext4_allocation_context *ac) { /* * Need to find what the right nomalized block num should be */ struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb); if (i_size_read(ac->ac_inode) >= sbi->s_mb_stream_request) { /* large inode which is using inode prealloc */ ac->ac_g_ex.fe_len = 10; } else { ac->ac_g_ex.fe_len = 2; } mb_debug("#%u: goal %lu blocks for meta-data group\n", current->pid, ac->ac_g_ex.fe_len); } ie, for large files for which we are using inode preallocation I am preallocating 10 blocks and for small files 2 blocks. The output also shows that when we are trying to allocate a new preallocation space we try to place the window closer to the data block. extent: lblk 0--335871, len 335872, pblk 45482, flags: 2ND_VISIT tst_extents: ns (Left 41) extent: lblk 335872--679935, len 344064, pblk 45483, flags: (none) tst_extents: ns (Left 40) extent: lblk 679936--1023999, len 344064, pblk 45484, flags: (none) tst_extents: ns (Left 39) extent: lblk 1024000--1368063, len 344064, pblk 45485, flags: (none) tst_extents: ns (Left 38) extent: lblk 1368064--1712127, len 344064, pblk 45487, flags: (none) tst_extents: ns (Left 37) extent: lblk 1712128--2056191, len 344064, pblk 45488, flags: (none) tst_extents: ns (Left 36) extent: lblk 2056192--2400255, len 344064, pblk 45489, flags: (none) tst_extents: ns (Left 35) extent: lblk 2400256--2744319, len 344064, pblk 45490, flags: (none) tst_extents: ns (Left 34) extent: lblk 2744320--3088383, len 344064, pblk 45491, flags: (none) tst_extents: ns (Left 33) extent: lblk 3088384--3432447, len 344064, pblk 6205571, flags: (none) tst_extents: ns (Left 32) extent: lblk 3432448--3776511, len 344064, pblk 6205572, flags: (none) tst_extents: ns (Left 31) extent: lblk 3776512--4120575, len 344064, pblk 6205573, flags: (none) tst_extents: ns (Left 30) extent: lblk 4120576--4464639, len 344064, pblk 6205574, flags: (none) tst_extents: ns (Left 29) extent: lblk 4464640--4808703, len 344064, pblk 6205575, flags: (none) tst_extents: ns (Left 28) extent: lblk 4808704--5013373, len 204670, pblk 6205576, flags: (none) tst_extents: ns (Left 27) extent: lblk 5013374--5185405, len 172032, pblk 6205577, flags: (none) tst_extents: ns (Left 26) extent: lblk 5185406--5357437, len 172032, pblk 6205578, flags: (none) tst_extents: ns (Left 25) extent: lblk 5357438--5529469, len 172032, pblk 6205579, flags: (none) tst_extents: ns (Left 24) extent: lblk 5529470--5701501, len 172032, pblk 6205580, flags: (none) tst_extents: ns (Left 23) extent: lblk 5701502--5873533, len 172032, pblk 3371269, flags: (none) tst_extents: ns (Left 22) extent: lblk 5873534--6045565, len 172032, pblk 3371270, flags: (none) tst_extents: ns (Left 21) extent: lblk 6045566--6217597, len 172032, pblk 3371271, flags: (none) tst_extents: ns (Left 20) extent: lblk 6217598--6389629, len 172032, pblk 3371272, flags: (none) tst_extents: ns (Left 19) extent: lblk 6389630--6561661, len 172032, pblk 3371273, flags: (none) tst_extents: ns (Left 18) extent: lblk 6561662--6733693, len 172032, pblk 3371274, flags: (none) tst_extents: ns (Left 17) extent: lblk 6733694--6905725, len 172032, pblk 3371275, flags: (none) tst_extents: ns (Left 16) extent: lblk 6905726--7077757, len 172032, pblk 3371276, flags: (none) tst_extents: ns (Left 15) extent: lblk 7077758--7249789, len 172032, pblk 3371277, flags: (none) tst_extents: ns (Left 14) extent: lblk 7249790--7421691, len 171902, pblk 3371278, flags: (none) tst_extents: ns (Left 13) extent: lblk 7421692--7593723, len 172032, pblk 1094153, flags: (none) tst_extents: ns The meta-data block 1094153 is closer to data block 1093893, tst_extents: nl (Left 13) <<<< OP = down header: magic=f30a entries=84 max=84 depth=0 generation=0 Down to level 2/2, end_blk=7593724 (Left 83) extent: lblk 7421692--7421951, len 260, pblk 1093893, flags: LEAF Eric, For the test you ran, If we update the preallocation window may be we will have better numbers. Can you try with different values in ext4_mb_normalize_meta_data_request ? -aneesh -- 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
