From 679ceace848e9fd570678396ffe1ef034e00e82d Mon Sep 17 00:00:00 2001 From: Michael Rubin Date: Fri, 20 Aug 2010 02:31:26 -0700 Subject: mm: exporting account_page_dirty This allows code outside of the mm core to safely manipulate page state and not worry about the other accounting. Not using these routines means that some code will lose track of the accounting and we get bugs. This has happened once already. Signed-off-by: Michael Rubin Signed-off-by: Sage Weil --- mm/page-writeback.c | 1 + 1 file changed, 1 insertion(+) (limited to 'mm/page-writeback.c') diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 37498ef61548..849d0ccbe914 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -1096,6 +1096,7 @@ void account_page_dirtied(struct page *page, struct address_space *mapping) task_io_account_write(PAGE_CACHE_SIZE); } } +EXPORT_SYMBOL(account_page_dirtied); /* * For address_spaces which do not use buffers. Just tag the page as dirty in -- cgit v1.2.2 From 546a1924224078c6f582e68f890b05b387b42653 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Tue, 24 Aug 2010 11:44:34 +1000 Subject: writeback: write_cache_pages doesn't terminate at nr_to_write <= 0 I noticed XFS writeback in 2.6.36-rc1 was much slower than it should have been. Enabling writeback tracing showed: flush-253:16-8516 [007] 1342952.351608: wbc_writepage: bdi 253:16: towrt=1024 skip=0 mode=0 kupd=0 bgrd=1 reclm=0 cyclic=1 more=0 older=0x0 start=0x0 end=0x0 flush-253:16-8516 [007] 1342952.351654: wbc_writepage: bdi 253:16: towrt=1023 skip=0 mode=0 kupd=0 bgrd=1 reclm=0 cyclic=1 more=0 older=0x0 start=0x0 end=0x0 flush-253:16-8516 [000] 1342952.369520: wbc_writepage: bdi 253:16: towrt=0 skip=0 mode=0 kupd=0 bgrd=1 reclm=0 cyclic=1 more=0 older=0x0 start=0x0 end=0x0 flush-253:16-8516 [000] 1342952.369542: wbc_writepage: bdi 253:16: towrt=-1 skip=0 mode=0 kupd=0 bgrd=1 reclm=0 cyclic=1 more=0 older=0x0 start=0x0 end=0x0 flush-253:16-8516 [000] 1342952.369549: wbc_writepage: bdi 253:16: towrt=-2 skip=0 mode=0 kupd=0 bgrd=1 reclm=0 cyclic=1 more=0 older=0x0 start=0x0 end=0x0 Writeback is not terminating in background writeback if ->writepage is returning with wbc->nr_to_write == 0, resulting in sub-optimal single page writeback on XFS. Fix the write_cache_pages loop to terminate correctly when this situation occurs and so prevent this sub-optimal background writeback pattern. This improves sustained sequential buffered write performance from around 250MB/s to 750MB/s for a 100GB file on an XFS filesystem on my 8p test VM. Cc: Signed-off-by: Dave Chinner Reviewed-by: Wu Fengguang Reviewed-by: Christoph Hellwig --- mm/page-writeback.c | 26 ++++++++++---------------- 1 file changed, 10 insertions(+), 16 deletions(-) (limited to 'mm/page-writeback.c') diff --git a/mm/page-writeback.c b/mm/page-writeback.c index c09ef5219cbe..a803f5e33471 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -985,22 +985,16 @@ continue_unlock: } } - if (wbc->nr_to_write > 0) { - if (--wbc->nr_to_write == 0 && - wbc->sync_mode == WB_SYNC_NONE) { - /* - * We stop writing back only if we are - * not doing integrity sync. In case of - * integrity sync we have to keep going - * because someone may be concurrently - * dirtying pages, and we might have - * synced a lot of newly appeared dirty - * pages, but have not synced all of the - * old dirty pages. - */ - done = 1; - break; - } + /* + * We stop writing back only if we are not doing + * integrity sync. In case of integrity sync we have to + * keep going until we have written all the pages + * we tagged for writeback prior to entering this loop. + */ + if (--wbc->nr_to_write <= 0 && + wbc->sync_mode == WB_SYNC_NONE) { + done = 1; + break; } } pagevec_release(&pvec); -- cgit v1.2.2