Hi Jaegeuk, On 2016/12/31 2:51, Jaegeuk Kim wrote: > This patch implements IO alignment by filling dummy blocks in DATA and NODE > write bios. If we can guarantee, for example, 32KB or 64KB for such the IOs, > we can eliminate underlying dummy page problem which FTL conducts in order to > close MLC or TLC partial written pages. > > Note that, > - it requires "-o mode=lfs". > - IO size should be power of 2, not exceed BIO_MAX_PAGES, 256. > - read IO is still 4KB. > - do checkpoint at fsync, if dummy NODE page was written.
Which scenario we can benefit from? Any numbers? I doubt that there are some potential side-effect points: - write amplification will be more serious than before - free space will be more fragmented since dummy blocks is separated in whole address space - there is less chance to merge small(unaligned) IOs in block layer Thoughts? Thanks,
