From 8f46dcaea8d9d1552f4071f1ddeeca4427c1d83a Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Tue, 14 Jul 2015 18:56:10 +0800 Subject: [PATCH] f2fs: expose f2fs_write_cache_pages If there are gced dirty pages and normal dirty pages in the mapping of one inode, we might writeback them alternately with discontinuous block address, resulting in low performance. This patch introduces f2fs_write_cache_pages with codes copied from write_cache_pages in mm/page-writeback.c. In this function, we refactor flow with two steps: 1) writeback all cold type pages. 2) writeback all non-cold type pages. By using this method, f2fs will writeback dirty pages with the same temperature in bunch mode, it makes writeouted block being with more continuous address, so they can be merged as much as possible in f2fs bio cache, and also it will reduce the chance of submiting small IO from block layer. Test environment: 8g nokia sd card (very old sd card, but it shows better effect when testing with this patch, and with a 32g kingston sd card, I didn't see much more improvement). Test step: 1. touch testfile; 2. truncate -s 512K testfile; 3. write all pages with odd index; 4. trigger gc by ioctl; 5. write all pages with even index; 6. time fsync testfile. before: real 0m0.402s user 0m0.000s sys 0m0.000s after: real 0m0.143s user 0m0.004s sys 0m0.004s Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim --- fs/f2fs/data.c | 136 ++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 135 insertions(+), 1 deletion(-) diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index ef30b59756c6..e58562e70da0 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include #include @@ -1127,6 +1128,139 @@ static int __f2fs_writepage(struct page *page, struct writeback_control *wbc, return ret; } +/* + * This function was copied from write_cche_pages from mm/page-writeback.c. + * The major change is making write step of cold data page separately from + * warm/hot data page. + */ +static int f2fs_write_cache_pages(struct address_space *mapping, + struct writeback_control *wbc, writepage_t writepage, + void *data) +{ + int ret = 0; + int done = 0; + struct pagevec pvec; + int nr_pages; + pgoff_t uninitialized_var(writeback_index); + pgoff_t index; + pgoff_t end; /* Inclusive */ + pgoff_t done_index; + int cycled; + int range_whole = 0; + int tag; + int step = 0; + + pagevec_init(&pvec, 0); +next: + if (wbc->range_cyclic) { + writeback_index = mapping->writeback_index; /* prev offset */ + index = writeback_index; + if (index == 0) + cycled = 1; + else + cycled = 0; + end = -1; + } else { + index = wbc->range_start >> PAGE_CACHE_SHIFT; + end = wbc->range_end >> PAGE_CACHE_SHIFT; + if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) + range_whole = 1; + cycled = 1; /* ignore range_cyclic tests */ + } + if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) + tag = PAGECACHE_TAG_TOWRITE; + else + tag = PAGECACHE_TAG_DIRTY; +retry: + if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) + tag_pages_for_writeback(mapping, index, end); + done_index = index; + while (!done && (index <= end)) { + int i; + + nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag, + min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1); + if (nr_pages == 0) + break; + + for (i = 0; i < nr_pages; i++) { + struct page *page = pvec.pages[i]; + + if (page->index > end) { + done = 1; + break; + } + + done_index = page->index; + + lock_page(page); + + if (unlikely(page->mapping != mapping)) { +continue_unlock: + unlock_page(page); + continue; + } + + if (!PageDirty(page)) { + /* someone wrote it for us */ + goto continue_unlock; + } + + if (step == 0 && !is_cold_data(page)) + goto continue_unlock; + if (step == 1 && is_cold_data(page)) + goto continue_unlock; + + if (PageWriteback(page)) { + if (wbc->sync_mode != WB_SYNC_NONE) + f2fs_wait_on_page_writeback(page, DATA); + else + goto continue_unlock; + } + + BUG_ON(PageWriteback(page)); + if (!clear_page_dirty_for_io(page)) + goto continue_unlock; + + ret = (*writepage)(page, wbc, data); + if (unlikely(ret)) { + if (ret == AOP_WRITEPAGE_ACTIVATE) { + unlock_page(page); + ret = 0; + } else { + done_index = page->index + 1; + done = 1; + break; + } + } + + if (--wbc->nr_to_write <= 0 && + wbc->sync_mode == WB_SYNC_NONE) { + done = 1; + break; + } + } + pagevec_release(&pvec); + cond_resched(); + } + + if (step < 1) { + step++; + goto next; + } + + if (!cycled && !done) { + cycled = 1; + index = 0; + end = writeback_index - 1; + goto retry; + } + if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0)) + mapping->writeback_index = done_index; + + return ret; +} + static int f2fs_write_data_pages(struct address_space *mapping, struct writeback_control *wbc) { @@ -1157,7 +1291,7 @@ static int f2fs_write_data_pages(struct address_space *mapping, mutex_lock(&sbi->writepages); locked = true; } - ret = write_cache_pages(mapping, wbc, __f2fs_writepage, mapping); + ret = f2fs_write_cache_pages(mapping, wbc, __f2fs_writepage, mapping); f2fs_submit_merged_bio(sbi, DATA, WRITE); if (locked) mutex_unlock(&sbi->writepages); -- 2.20.1