Hi, > -----Original Message----- > From: Jaegeuk Kim [mailto:jaegeuk.kim@xxxxxxxxxxx] > Sent: Thursday, November 28, 2013 11:33 AM > To: Chao Yu > Cc: linux-fsdevel@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx; '谭姝' > Subject: RE: [f2fs-dev] [PATCH] f2fs: readahead contiguous pages for restore_node_summary > > Hi, > > 2013-11-28 (목), 09:26 +0800, Chao Yu: > > Hi Kim, > > > > > -----Original Message----- > > > From: Jaegeuk Kim [mailto:jaegeuk.kim@xxxxxxxxxxx] > > > Sent: Wednesday, November 27, 2013 4:19 PM > > > To: Chao Yu > > > Cc: linux-fsdevel@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx; '谭姝' > > > Subject: RE: [f2fs-dev] [PATCH] f2fs: readahead contiguous pages for restore_node_summary > > > > > > Hi, > > > > > > 2013-11-27 (수), 15:58 +0800, Chao Yu: > > > > Hi Kim, > > > > > > > > > -----Original Message----- > > > > > From: Jaegeuk Kim [mailto:jaegeuk.kim@xxxxxxxxxxx] > > > > > Sent: Wednesday, November 27, 2013 1:30 PM > > > > > To: Chao Yu > > > > > Cc: linux-fsdevel@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx; 谭姝 > > > > > Subject: Re: [f2fs-dev] [PATCH] f2fs: readahead contiguous pages for restore_node_summary > > > > > > > > > > Hi Chao, > > > > > > > > > > It seems that we already have a readahed function for node pages, > > > > > ra_node_page(). > > > > > So, we don't make a page list for this, but can use the node_inode's > > > > > page cache. > > > > > > > > So you mean it's waste to release page list with updated data after we > > > > finish work in restore_node_summary, right? > > > > > > Right. > > > > So how about add all pages of page list to node_inode's address space by > > add_to_page_cache_lru() with arg sum_entry->nid? > > I don't think it's proper way to use add_to_page_cache_lru() directly. This is the way used in VM readahead(i.e. read_pages/mpage_readpages/ read_cache_pages). So what you worry about is that using lonely add_to_page_cache_lru() may cause exception, is it? > > > > > > > > > > > > > > > > > > > > So how about writing ra_node_pages() which use the node_inode's page > > > > > cache? > > > > > > > > Hmm, so ra_node_pages is introduced for read node_inode's pages which are > > > > logical contiguously? and it also could take place of ra_node_page? > > > > > > Ah. The ra_node_page() read a node page ahead for a given node id. > > > So it doesn't match exactly between ra_node_page() and ra_node_pages() > > > that I suggested. > > > So how about reading node pages and then caching some of them in the > > > page cache, node_inode's address space? > > > > Got it, > > If we do not use the method above, we should search the NAT for nid number > > as the index of node_inode's page by the specified node page blkaddr, that costs > > a lot. > > How do you think? > > 1. grab_cache_page(node_footer->nid); > 2. memcpy(); > 3. SetPageUptodate(); > 4. f2fs_put_page(); It could be. This make ra_node_pages() synchronized, because we should read node_footer->nid from updated node page before we cache node pages, and we will still use page list to pass the updated page. Why not introduce f2fs_cache_node_pages() include your code to cache node pages after ra_node_pages()? Thanks, Yu > > Thanks, > > > > > > > > > Thanks, > > > > > > > > > > > > > > > > > > > > > Thanks, > > > > > > > > > > 2013-11-22 (금), 15:48 +0800, Chao Yu: > > > > > > If cp has no CP_UMOUNT_FLAG, we will read all pages in whole node segment > > > > > > one by one, it makes low performance. So let's merge contiguous pages and > > > > > > readahead for better performance. > > > > > > > > > > > > Signed-off-by: Chao Yu <chao2.yu@xxxxxxxxxxx> > > > > > > --- > > > > > > fs/f2fs/node.c | 89 +++++++++++++++++++++++++++++++++++++++----------------- > > > > > > 1 file changed, 63 insertions(+), 26 deletions(-) > > > > > > > > > > > > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c > > > > > > index 4ac4150..81e704a 100644 > > > > > > --- a/fs/f2fs/node.c > > > > > > +++ b/fs/f2fs/node.c > > > > > > @@ -1572,47 +1572,84 @@ int recover_inode_page(struct f2fs_sb_info *sbi, struct page *page) > > > > > > return 0; > > > > > > } > > > > > > > > > > > > +/* > > > > > > + * ra_sum_pages() merge contiguous pages into one bio and submit. > > > > > > + * these pre-readed pages are linked in pages list. > > > > > > + */ > > > > > > +static int ra_sum_pages(struct f2fs_sb_info *sbi, struct list_head *pages, > > > > > > + int start, int nrpages) > > > > > > +{ > > > > > > + struct page *page; > > > > > > + int page_idx = start; > > > > > > + > > > > > > + for (; page_idx < start + nrpages; page_idx++) { > > > > > > + /* alloc temporal page for read node summary info*/ > > > > > > + page = alloc_page(GFP_NOFS | __GFP_ZERO); > > > > > > + if (!page) { > > > > > > + struct page *tmp; > > > > > > + list_for_each_entry_safe(page, tmp, pages, lru) { > > > > > > + list_del(&page->lru); > > > > > > + unlock_page(page); > > > > > > + __free_pages(page, 0); > > > > > > + } > > > > > > + return -ENOMEM; > > > > > > + } > > > > > > + > > > > > > + lock_page(page); > > > > > > + page->index = page_idx; > > > > > > + list_add_tail(&page->lru, pages); > > > > > > + } > > > > > > + > > > > > > + list_for_each_entry(page, pages, lru) > > > > > > + submit_read_page(sbi, page, page->index, READ_SYNC); > > > > > > + > > > > > > + f2fs_submit_read_bio(sbi, READ_SYNC); > > > > > > + return 0; > > > > > > +} > > > > > > + > > > > > > int restore_node_summary(struct f2fs_sb_info *sbi, > > > > > > unsigned int segno, struct f2fs_summary_block *sum) > > > > > > { > > > > > > struct f2fs_node *rn; > > > > > > struct f2fs_summary *sum_entry; > > > > > > - struct page *page; > > > > > > + struct page *page, *tmp; > > > > > > block_t addr; > > > > > > - int i, last_offset; > > > > > > - > > > > > > - /* alloc temporal page for read node */ > > > > > > - page = alloc_page(GFP_NOFS | __GFP_ZERO); > > > > > > - if (!page) > > > > > > - return -ENOMEM; > > > > > > - lock_page(page); > > > > > > + int bio_blocks = MAX_BIO_BLOCKS(max_hw_blocks(sbi)); > > > > > > + int i, last_offset, nrpages, err = 0; > > > > > > + LIST_HEAD(page_list); > > > > > > > > > > > > /* scan the node segment */ > > > > > > last_offset = sbi->blocks_per_seg; > > > > > > addr = START_BLOCK(sbi, segno); > > > > > > sum_entry = &sum->entries[0]; > > > > > > > > > > > > - for (i = 0; i < last_offset; i++, sum_entry++) { > > > > > > - /* > > > > > > - * In order to read next node page, > > > > > > - * we must clear PageUptodate flag. > > > > > > - */ > > > > > > - ClearPageUptodate(page); > > > > > > + for (i = 0; i < last_offset; i += nrpages, addr += nrpages) { > > > > > > > > > > > > - if (f2fs_readpage(sbi, page, addr, READ_SYNC)) > > > > > > - goto out; > > > > > > + nrpages = min(last_offset - i, bio_blocks); > > > > > > + /* read ahead node pages */ > > > > > > + err = ra_sum_pages(sbi, &page_list, addr, nrpages); > > > > > > + if (err) > > > > > > + return err; > > > > > > > > > > > > - lock_page(page); > > > > > > - rn = F2FS_NODE(page); > > > > > > - sum_entry->nid = rn->footer.nid; > > > > > > - sum_entry->version = 0; > > > > > > - sum_entry->ofs_in_node = 0; > > > > > > - addr++; > > > > > > + list_for_each_entry_safe(page, tmp, &page_list, lru) { > > > > > > + > > > > > > + lock_page(page); > > > > > > + if(PageUptodate(page)) { > > > > > > + rn = F2FS_NODE(page); > > > > > > + sum_entry->nid = rn->footer.nid; > > > > > > + sum_entry->version = 0; > > > > > > + sum_entry->ofs_in_node = 0; > > > > > > + sum_entry++; > > > > > > + } else { > > > > > > + err = -EIO; > > > > > > + } > > > > > > + > > > > > > + list_del(&page->lru); > > > > > > + unlock_page(page); > > > > > > + __free_pages(page, 0); > > > > > > + } > > > > > > } > > > > > > - unlock_page(page); > > > > > > -out: > > > > > > - __free_pages(page, 0); > > > > > > - return 0; > > > > > > + return err; > > > > > > } > > > > > > > > > > > > static bool flush_nats_in_journal(struct f2fs_sb_info *sbi) > > > > > > > > > > -- > > > > > Jaegeuk Kim > > > > > Samsung > > > > > > > > > > -- > > > Jaegeuk Kim > > > Samsung > > > > -- > 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
