On Thu 21-03-13 17:43:52, Kazuya Mio wrote:

2013/03/20 4:31, Jan Kara wrote:

quoted

 I'm not sure I understand. Looking into dio_send_cur_page() it seems may
prematurely submit the bio if sdio->boundary is set - in that case we
should probably first try to add the page to the bio and submit the bio
only after that. Is that what you mean?

I think the direct I/O works for each page into buffer_head by the following
three steps:
1. submit sdio->bio if sdio->boudary is set
2. add sdio->cur_page to sdio->bio by dio_new_bio() or dio_bio_add_page()
3. set the curret page to sdio->cur_page in submit_page_section()

It is true that dio_send_cur_page() submits the bio if sdio->boudary is set.
However, at this time, this bio does not contain sdio->cur_page and
the current page do_direct_IO() passed.

  Sorry for not getting to you earlier. So we agree in our analysis. Do you
agree with the attached patch? Does it help your workload?

									Honza
-- 
Jan Kara [off-list ref]
SUSE Labs, CR