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If there is no candidates for shrinking slab entries, we don't need to traverse
any trees at all.
Reviewed-by: Chao Yu <chao2.yu@samsung.com>
[Jaegeuk Kim: fix missing initialization reported by Yunlei He]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
It would be better to use atomic variable for total_extent_tree.
Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
For direct IO, f2fs only allocate new address for the block which is not
exist in the disk before, its mapping info should not exist in extent
cache previously, so here we do not need to call f2fs_drop_largest_extent
to drop related cache.
Due to no more callers for f2fs_drop_largest_extent now, kill it.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
While handling extent trees, we can enter into a reclaiming path anytime.
If it tries to release some extent nodes in the same extent tree,
write_lock(&et->lock) would be hanged.
In order to avoid the deadlock, we can just skip it.
Note that, if it is an unreferenced tree, we should get write_lock(&et->lock)
successfully and release all of therein nodes.
Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
In f2fs_shrink_extent_tree we should stop shrink flow if we have already
shrunk enough nodes in extent cache.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch adds a new helper __try_update_largest_extent for cleanup.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Fix 2 potential problems:
1. when largest extent needs to be invalidated, it will be reset in
__drop_largest_extent, which makes __is_extent_same after always
return false, and largest extent unchanged. Now we update it properly.
2. when extent is split and the latter part remains in tree, next_en
should be the latter part instead of next extent of original extent.
It will cause merge failure if there is in-place update, although
there is not, I think this fix will still makes codes less ambiguous.
This patch also simplifies codes of invalidating extents, and optimizes the
procedues that split extent into two.
There are a few modifications after last patch:
1. prev_en now is updated properly.
2. more codes and branches are simplified.
Signed-off-by: Fan li <fanofcode.li@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
now we update extent by range, fofs may not be on the largest
extent if the new extent overlaps with it. so add a new function
to drop largest extent properly.
Signed-off-by: Fan li <fanofcode.li@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
When shrinking extent cache, we have two steps in the flow:
1) shrink objects which are unreferenced by inodes;
2) shrink objects from LRU list of extent cache.
In step 1, if we haven't shrunk enough number of objects, we will try
step 2, but before that we didn't update the searching position which
may point to last inode index in global extent tree, result in failing
to shrink objects by traversing the all inodes' extent tree.
In this patch, we reset searching position to beginning of global extent
tree for fixing.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Rename trace_f2fs_update_extent_tree to trace_f2fs_update_extent_tree_range,
then expand and enable it to trace in batches extent info updates.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch introduce a new helper f2fs_update_extent_tree_range which can
do extent mapping update at a specified range.
The main idea is:
1) punch all mapping info in extent node(s) which are at a specified range;
2) try to merge new extent mapping with adjacent node, or failing that,
insert the mapping into extent tree as a new node.
In order to see the benefit, I add a function for stating time stamping
count as below:
uint64_t rdtsc(void)
{
uint32_t lo, hi;
__asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
return (uint64_t)hi << 32 | lo;
}
My test environment is: ubuntu, intel i7-3770, 16G memory, 256g micron ssd.
truncation path: update extent cache from truncate_data_blocks_range
non-truncataion path: update extent cache from other paths
total: all update paths
a) Removing 128MB file which has one extent node mapping whole range of
file:
1. dd if=/dev/zero of=/mnt/f2fs/128M bs=1M count=128
2. sync
3. rm /mnt/f2fs/128M
Before:
total count average
truncation: 7651022 32768 233.49
Patched:
total count average
truncation: 3321 33 100.64
b) fsstress:
fsstress -d /mnt/f2fs -l 5 -n 100 -p 20
Test times: 5 times.
Before:
total count average
truncation: 5812480.6 20911.6 277.95
non-truncation: 7783845.6 13440.8 579.12
total: 13596326.2 34352.4 395.79
Patched:
total count average
truncation: 1281283.0 3041.6 421.25
non-truncation: 7355844.4 13662.8 538.38
total: 8637127.4 16704.4 517.06
1) For the updates in truncation path:
- we can see updating in batches leads total tsc and update count reducing
explicitly;
- besides, for a single batched updating, punching multiple extent nodes
in a loop, result in executing more operations, so our average tsc
increase intensively.
2) For the updates in non-truncation path:
- there is a little improvement, that is because for the scenario that we
just need to update in the head or tail of extent node, new interface
optimize to update info in extent node directly, rather than removing
original extent node for updating and then inserting that updated one
into cache as new node.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
In __lookup_extent_tree_ret we will not try to find neighbor nodes if
we find the target node, in this condition, we will lost the chance to
merge the new mapping with exist extent node later.
So our extent cache of inode will be fragmented after overwrite exist
file, we can see the number of extent node increases intensively in
following test case:
dd if=/dev/zero of=/mnt/f2fs/4m bs=4K count=1024
Extent Cache:
- Hit Count: L1-1:0 L1-2:0 L2:0
- Hit Ratio: 0% (0 / 3072)
- Inner Struct Count: tree: 1, node: 1
dd if=/dev/zero of=/mnt/f2fs/4m bs=4K count=1024 conv=notrunc
Extent Cache:
- Hit Count: L1-1:2048 L1-2:0 L2:0
- Hit Ratio: 33% (2048 / 6144)
- Inner Struct Count: tree: 1, node: 961
This patch fixes to lookup neighbors of target node for further
merging.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch splits __insert_extent_tree_ret into __try_merge_extent_node &
__insert_extent_tree for code readability.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
After commit 0f825ee6e8 ("f2fs: add new interfaces for extent tree"),
f2fs_init_extent_tree becomes the only caller of __insert_extent_tree, and
in f2fs_init_extent_tree, we will only insert extent node in an empty tree,
so __try_{back,front}_merge in __insert_extent_tree will never be called.
This patch removes these dead codes, besides, rename __insert_extent_tree
to __init_extent_tree for readability.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch alters to replace total hit stat with rbtree hit stat,
and then adjust showing of extent cache stat:
Hit Count:
L1-1: for largest node hit count;
L1-2: for last cached node hit count;
L2: for extent node hit after lookuping in rbtree.
Hit Ratio:
ratio (hit count / total lookup count)
Inner Struct Count:
tree count, node count.
Before:
Extent Hit Ratio: 0 / 2
Extent Tree Count: 3
Extent Node Count: 2
Patched:
Exten Cacache:
- Hit Count: L1-1:4871 L1-2:2074 L2:208
- Hit Ratio: 1% (7153 / 550751)
- Inner Struct Count: tree: 26560, node: 11824
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch adds to stat the hit count of largest/cached node for showing
in debugfs.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
In f2fs_lookup_extent_tree, et->cached_en was read and updated with only
read lock held,
it could cause __lookup_extent_tree within return entirely wrong
extent_node, if other
thread update et->cached_en just before __lookup_extent_tree return.
However, there are two things about this patch that need to be noticed:
1. It does no good to arrange the order of concurrent read/write, the result
would still
be random in such case.
2. It's built on this assumption: the mix up of reads and writes on a single
pointer would
not make the pointer partially wrong at any time. Please let me know if I'm
wrong, thx.
Signed-off-by: Fan li <fanofcode.li@samsung.com>
Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Add a lookup and a insertion interface for extent tree.
The new lookup return the insert position and the prev/next
extents closest to the offset we lookup when find no match.
The new insertion uses above parameters to improve performance.
There are three possible insertions after the lookup in
f2fs_update_extent_tree, two of them insert parts of removed extent
back to tree, since no merge happens during this process, new insertion
skips the merge check in this scanario; the another insertion inserts a
new extent to tree, new insertion uses prev/next extent and insert
position to insert this extent directly, and save the time of searching
down the tree.
As long as tree remains unchanged between lookup and insertion, this
would work fine. And the new lookup would be useful when add
multi-blocks extent support for insertion interface.
Signed-off-by: Fan li <fanofcode.li@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Variables for recording extent cache ratio info were updated without
protection, this patch tries to alter them to atomic_t type for more
accurate stat.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch moves extent cache related code from data.c into extent_cache.c
since extent cache is independent feature, and its codes are not relate to
others in data.c, it's better for us to maintain them in separated place.
There is no functionality change, but several small coding style fixes
including:
* rename __drop_largest_extent to f2fs_drop_largest_extent for exporting;
* rename misspelled word 'untill' to 'until';
* remove unneeded 'return' in the end of f2fs_destroy_extent_tree().
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
