Coly Li wrote: > Thanks for the feedback :-) > > Alex Tomas wrote: >> hmm. so you trade 265% degradation of creation for 40% improvement of >> unlink? >> > 265% degradation is only for creating 50000 empty directories. This is not a common case. > There are 13% improvement on create 15 files in each directories. Total time on creating these > directories and files are 25m6s VS. 24m86s, indeed, dir inode reservation is a little faster. Sorry a typo here, it's 25m6s VS. 24m7.86s. > > Maybe most of the people will not create dozens of empty directories in their applications, > therefore IMHO the 265% degradation is acceptable. > > If user really need to create so many empty directories, they also can mount the file system without > dir inode reservation to get better performance. > >> thanks, Alex >> >> Coly Li wrote: >>> normal ext4 ext4 with dir inode reservation >>> mount options: -o data=writeback -o >>> data=writeback,dir_ireserve=low >>> Create dirs: real 0m49.101s real 2m59.703s >>> Create files: real 24m17.962s real 21m8.161s >>> Unlink all: real 24m43.788s real 17m29.862s >>> Creating dirs with dir inode reservation is slower than normal ext4 as >>> predicted, because allocating >>> directory inodes in non-linear order will cause extra hard disk >>> seeking and block I/O. Creating >>> files with dir inode reservation is 13% faster than normal ext4. >>> Unlink all the directories and >>> files is 29.2% faster as expected. >>> When number of directories is increased, the performance improvement >>> will be more considerable. More >>> benchmark result will be posted here if necessary, because I need more >>> time to run more test cases. > -- Coly Li SuSE PRC Labs - 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
