2013/1/18, Jaegeuk Kim <jaegeuk.kim@xxxxxxxxxxx>: > 2013-01-18 (금), 17:57 +0900, Namjae Jeon: >> 2013/1/18, Jaegeuk Kim <jaegeuk.kim@xxxxxxxxxxx>: >> > 2013-01-18 (금), 16:58 +0900, Namjae Jeon: >> >> 2013/1/18, Jaegeuk Kim <jaegeuk.kim@xxxxxxxxxxx>: >> >> > If some small bios of dirty node pages are supposed to be issued >> >> > during >> >> > the >> >> > sequential data writes, there-in well-produced consecutive data bios >> >> > are >> >> > able >> >> > to be split by the small node bios, resulting in performance >> >> > degradation. >> >> > So, let's collect a number of dirty node pages until reaching a >> >> > threshold. >> >> > And, by default, I set the threshold as 2MB, a segment size. >> >> > >> >> > This improves sequential write performance on i5, 512GB SSD (830 w/ >> >> > SATA2) >> >> > as >> >> > follows. >> >> > Before: 231 MB/s -> After: 255 MB/s >> >> > >> >> > Signed-off-by: Jaegeuk Kim <jaegeuk.kim@xxxxxxxxxxx> >> >> > --- >> >> > fs/f2fs/node.c | 17 +++++++++++------ >> >> > 1 file changed, 11 insertions(+), 6 deletions(-) >> >> > >> >> > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c >> >> > index f177c01..9bda63c 100644 >> >> > --- a/fs/f2fs/node.c >> >> > +++ b/fs/f2fs/node.c >> >> > @@ -1124,6 +1124,12 @@ static int f2fs_write_node_page(struct page >> >> > *page, >> >> > return 0; >> >> > } >> >> > >> >> > +/* >> >> > + * It is very important to gather dirty pages and write at once, so >> >> > that we >> >> > can >> >> > + * submit a big bio without interfering other data writes. >> >> > + * Be default, 512 pages (2MB), a segment size, is quite >> >> > reasonable. >> >> > + */ >> >> > +#define COLLECT_DIRTY_NODES 512 >> >> Hi Jaeguek. >> >> It is just my opinion. >> >> One of f2fs advantages is that user can set segment size to fit own >> >> device. >> >> For future, Is it not good to use segment size set by user(from >> >> superblock) instead of fixed size ? >> > >> > At this moment, it's very hard to change the segment size due to many >> > hardcoded data structures such as SSA, bitmaps, etc. >> > Instead, I proposed something like section and zone which are based on >> > segment. >> > But, somebody will be able to do later. :) >> Reviewed-by: Namjae Jeon <namjae.jeon@xxxxxxxxxxx> >> Okay, I think It is better if you add TODO comment about this to be >> fixed by the other. >> >> Talk Incidentally, let me ask you other thing. >> get_meta_page never return NULL about allocate page and readpage. >> Is there any reason it try to infinitely retry about two case ? > > That is just to handle errors more easily especially for file system > metadata operations. > Definitely, we need to consider all the error handling codes in more > detail by using the fault-injection facility later. > Thanks, Okay, I see. Thanks! > > -- > Jaegeuk Kim > Samsung > -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
