Hi Pengyang, Could you please shed a light on some performance gains by this?
Thanks, On 05/20, Hou Pengyang wrote: > This patches are to designed to optimize NAT/SIT flushing procedure: > > patch 1) -- patch 3): > > during flush_nat_entries, we do: > 1) gang_lookup a radix tree, find all the dirty nat_entry_set; > 2) sort nat_entry_set by nat_entry_set->entry_cnt, in order to > write to journal as much as possible to avoid unnessary IO. > > This patch optimize the look_up & sort algorithm by introducing an array: > > f2fs_nm_info->dirty_set[NAT_ENTRY_PER_BLOCK+1]; > (struct list_head dirty_set[NAT_ENTRY_PER_BLOCK + 1]) > > dirty_set[1] links all nat_entry_set whose entry_cnt is 1 > dirty_set[2] links all nat_entry_set whose entry_cnt is 2 > ...... > dirty_set[N] links all nat_entry_set whose entry_cnt is N > > as one NAT block has NAT_ENTRY_PER_BLOCK entries at MOST, so there should NOT > be one nat_entry_set whose entry_cnt is larger than NAT_ENTRY_PER_BLOCK. > > So it is enough for f2fs_nm_info->dirty_set to link all nat_entry_sets in > system. > > Update: > we update nat_entry_set in real-time, e.g originally > nat_entry_set->entry_cnt is > 1, and licked by dirty_set[1]; then call __set_nat_cache_dirty to increase > nat_entry's > entry_cnt, we move this nat_entry_set ot dirty_set[2]'s tail, no need to > compare. > > Flush: > when flush dirty nat_entry_set, we just flush nat_entry_set from > f2fs_nm_info->dirty_set[0] to f2fs_nm_info->dirty_set[NAT_ENTRY_PER_BLOCK], > where > gang_lookup and sort can be avoid. > > footprint of this algorithm: sizeof(struct list_head)*NAT_ENTRY_PER_BLOCK > = 8*455 = 3.6k bytes > > Same for SIT. > > In patch 5), we use array to manage sit_entry_sets instead of list, which > can avoid list travel, and there is no need to alloc/free lab memory. > It is low footrpint consuming. > > Hou Pengyang (5): > f2fs: use bucket sort to avoid tree lookup and list sort when nat flushing > f2fs: reconstruct sit flushing code > f2fs: use bucket sort to avoid list sort when flush sit entries > f2fs: avoid unnecessary to_journal checking > f2fs: use an array to record sit_entry_set info to make sort fast > > fs/f2fs/f2fs.h | 5 +- > fs/f2fs/node.c | 79 ++++++++----------- > fs/f2fs/segment.c | 227 > ++++++++++++++++++++++++++---------------------------- > fs/f2fs/segment.h | 2 +- > 4 files changed, 147 insertions(+), 166 deletions(-) > > -- > 2.10.1 > > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
