On Fri, Aug 27, 2021 at 5:43 PM Chao Yu <[email protected]> wrote: > > On 2021/8/27 23:22, Daeho Jeong wrote: > >> I'd like to add a fixed chunk/hole fragmentation mode in addition, then > >> userspace can control the fragmented chunk/hole with fixed size. > >> > >> How do you think of renaming "fragment:block" to "fragment:rand_block", and > >> then I can add "fragment:fixed_block" option and its logic in addition? > >> > > > > The reason I added the randomness on these values is the segment > > selection in SSR mode. > > If all the segments have the same free block counts, f2fs will > > allocate a new segment sequentially in SSR. > > I'm fine with this, since test program can customize different fragment > degree on segments by setting different chunk/hole size. >
Got it. Sounds good~ > > This was what I didn't want. Plus, in the real world, the size of hole > > and chunk will be different in different segments. > > > > But, if you think we need this "fragment:fixed_block" mode, I am happy > > to have it. :) > > Thanks a lot. :) > > As you said it needs to be aligned to real world fragmentation, I notice that: > with this way, we can't simulate similar fragment in FTL, due to its page > mapping architecture, all fragmented data/node in filesystem will be written > sequentially into its blocks. > > In order to simulate fragment in FTL, we need to: > - write data (chunk size) with dummy pages (hole size) to devices > - issue discards on those holes > > I guess fragmenting device (erase blocks) at the same time wouldn't be > original intention of this patch, right? > > Thanks, > Yes, I just meant filesystem fragmentation as I wrote in the comment. > > > >> Do we need to consider multiple thread scenario? in such case, > >> .fragment_remained_chunk may update randomly. > >> > >> In addition, multiple log headers share one .fragment_remained_chunk, > >> it may cause unexpected result, it means there may be continuous holes > >> or chunks in locality due to swithing between different log headers. > >> > >> Thanks, > >> > > > > Oh, I overlooked that point. I am going to add the variable for each > > segment as you said before. > > > > Thanks, > > _______________________________________________ Linux-f2fs-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
