Hi Zheng, Thanks for working on this! I've included your v5 extent status tree patches into the ext4 dev tree. I will start doing further testing. I suspected it wouldn't make a different, but I tested and confirmed that your patches don't help fix the regression introduced by the patch: disable-merging-of-uninitialized-extents As a result, I've moved the following patches to the unstable portion of the ext4 patch queue, pending further investigation and discussion: disable-merging-of-uninitialized-extents remove-unnecessary-wait-for-extent-coversion-in-ext4_fallocate ext4_split_extent_should_take_care_of_extent_zeroout I will be running a full set of tests and looking more deeply at the patches, but for now I want to get them into linux-next for more testing and review. Cheers, - Ted On Fri, Feb 08, 2013 at 04:43:56PM +0800, Zheng Liu wrote: > Hi all, > > This is my fifth try to implement the second step of extent status tree. > The patch set can be divided into the following parts. > > Patch 1/10 > This patch refines the extent status tree > > Patch 2/10-6/10 > These patches try to track all extent status in extent status tree and > make it as a extent cache. In extent_status structure bit field is removed > because we get some warnings from 'sparse'. Now es_pblk and es_status are > manipulated by ext4_es_*_pblock and ext4_es_*_status directly. Currently > when an unwritten extent is allocated, we never know it from map->m_flags > because ext4_ext_map_blocks doesn't return EXT4_MAP_UNWRITTEN flag. A > patch fixes it and we can determine the extent status according to m_flags. > According to Jan's feedback, we put the hole into extent cache to avoid > to access extent tree in disk as far as possible. Here if the whole file > is a hole, this hole will not be cached in extent status tree because it > is always splitted immediately. Meanwhile the hole will not be cached > when ext4_da_map_blocks looks up a block mapping because this hole will be > as a delayed extent later. > > Patch 7/10-8/10 > This two patches try to reclaim memory from extent status tree when we > are under a high memeory pressure. > > Patch 9/10-10/10 > Thses patches are picked up again from 1st version because I aware that > they could remove a bogus wait in ext4_ind_direct_IO when dioread_nolock > is enabled. After applied them, the latency of dio read can be reduced. > > I measure it using fio and the result shows as below. > > config file > ----------- > [global] > ioengine=psync > direct=1 > bs=4k > thread > group_reporting > directory=/mnt/sda1/ > filename=testfile > filesize=10g > size=10g > runtime=120 > iodepth=16 > > [fio] > rw=randrw > numjobs=4 > > result > ------ > w/ bogus wait > read : io=1508.1MB, bw=12876KB/s, iops=3218 , runt=120001msec > clat (usec): min=128 , max=268738 , avg=718.62, stdev=3703.97 > lat (usec): min=128 , max=268739 , avg=718.78, stdev=3703.97 > write: io=1505.2MB, bw=12843KB/s, iops=3210 , runt=120001msec > clat (usec): min=47 , max=991727 , avg=520.94, stdev=3451.63 > lat (usec): min=47 , max=991727 , avg=521.31, stdev=3451.63 > > w/o bogus wait > read : io=1576.4MB, bw=13451KB/s, iops=3362 , runt=120001msec > clat (usec): min=128 , max=283906 , avg=685.88, stdev=2762.64 > lat (usec): min=128 , max=283907 , avg=686.05, stdev=2762.64 > write: io=1577.9MB, bw=13458KB/s, iops=3364 , runt=120001msec > clat (usec): min=48 , max=977942 , avg=498.97, stdev=3093.08 > lat (usec): min=48 , max=977943 , avg=499.33, stdev=3093.08 > > From the result we can see that the avg. of latency could be reduced a little. > > changelog: > v5 <- v4: > - drop a patch that removes EXT4_MAP_FROM_CLUSTER flag > (I will revise it in the patch set of get_block_t refinement) > - fold original patch 3/9 into patch 4/9 > - manipulate es_pblk and es_status directly > (bit field is removed because it causes some warnings from 'sparse') > - let ext4_ext_map_blocks return EXT4_MAP_UNWRITTEN flag > - rename ext4_es_find_extent with ext4_es_find_delayed_extent > - add hole status and put hole into extent status tree as a cache > - convert unwritten extents from extent status tree in ext4_ext_direct_IO > and end_io callback > - remove a bogus wait in ext4_ind_direct_IO when dioread_nolock is enabled > > v4 <- v3: > - register a normal shrinker to reclaim extent from extent status tree > > v3 <- v2: > - use prune_super() to reclaim extents from extent status tree > - stashed es_status into es_pblk > - remove single extent cache > - rebase against 3.8-rc4 > > v2 <- v1: > - drop patches that try to improve unwritten extent conversion > - remove EXT4_MAP_FROM_CLUSTER flag > - add tracepoint for ext4_es_lookup_extent() > - drop a patch, which tries to fix a warning when bigalloc and delalloc > are enabled > - add a shrinker to reclaim memory from extent status tree > - rebase against 3.8-rc2 > > v4: http://lwn.net/Articles/536037/ > v3: http://lwn.net/Articles/533730/ > v2: http://lwn.net/Articles/532446/ > v1: http://lwn.net/Articles/531065/ > > As always, any comments or feedbacks are welcome. > > FWIW, when I try to implement patch 3/10, I realize that get_block_t and > *_map_blocks functions need to be refactored because in ext4 we already > have six get_block_t functions > - ext4_get_block > - ext4_get_block_write > - ext4_get_block_write_nolock > - noalloc_get_block_write > - ext4_da_get_block_prep > - _ext4_get_block > > and four *_map_blocks > - ext4_map_blocks > - ext4_da_map_blocks > - ext4_ext_map_blocks > - ext4_ind_map_blocks > > So I am planning to refine them. First I will try to split ext4_map_blocks > into two parts, e.g. ext4_map_blocks_read and ext4_map_blocks_write, and > then try other cleanups and improvmentes. > > Thanks, > - Zheng > > Zheng Liu (10): > ext4: refine extent status tree > ext4: add physical block and status member into extent status tree > ext4: let ext4_ext_map_blocks return EXT4_MAP_UNWRITTEN flag > ext4: track all extent status in extent status tree > ext4: lookup block mapping in extent status tree > ext4: remove single extent cache > ext4: adjust some functions for reclaiming extents from extent status > tree > ext4: reclaim extents from extent status tree > ext4: convert unwritten extents from extent status tree in end_io > ext4: remove bogus wait for unwritten extents in ext4_ind_direct_IO > > fs/ext4/ext4.h | 21 +- > fs/ext4/ext4_extents.h | 6 - > fs/ext4/extents.c | 211 ++++-------- > fs/ext4/extents_status.c | 779 +++++++++++++++++++++++++++++++++++--------- > fs/ext4/extents_status.h | 84 ++++- > fs/ext4/file.c | 16 +- > fs/ext4/indirect.c | 5 - > fs/ext4/inode.c | 148 +++++++-- > fs/ext4/move_extent.c | 3 - > fs/ext4/page-io.c | 8 +- > fs/ext4/super.c | 8 +- > include/trace/events/ext4.h | 207 ++++++++++-- > 12 files changed, 1075 insertions(+), 421 deletions(-) > > -- > 1.7.12.rc2.18.g61b472e > -- 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
