On Mon 21-11-11 21:03:45, Wu Fengguang wrote: > When dd in 512bytes, generic_perform_write() calls > balance_dirty_pages_ratelimited() 8 times for the same page, but > obviously the page is only dirtied once. > > Fix it by accounting nr_dirtied at page dirty time. Well, but after this change, the interface balance_dirty_ratelimited_nr() is strange because the argument is only used for per-CPU ratelimiting and not for per-task ratelimiting... So if you do this switch then I'd also switch bdp_ratelimits to get consistent results and a clean interface and completely kill balance_dirty_pages_ratelimited_nr(). Honza > > Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx> > --- > mm/page-writeback.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > --- linux-next.orig/mm/page-writeback.c 2011-11-17 20:57:13.000000000 +0800 > +++ linux-next/mm/page-writeback.c 2011-11-17 20:57:15.000000000 +0800 > @@ -1224,8 +1224,6 @@ void balance_dirty_pages_ratelimited_nr( > if (bdi->dirty_exceeded) > ratelimit = min(ratelimit, 32 >> (PAGE_SHIFT - 10)); > > - current->nr_dirtied += nr_pages_dirtied; > - > preempt_disable(); > /* > * This prevents one CPU to accumulate too many dirtied pages without > @@ -1734,6 +1732,7 @@ void account_page_dirtied(struct page *p > __inc_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE); > __inc_bdi_stat(mapping->backing_dev_info, BDI_DIRTIED); > task_io_account_write(PAGE_CACHE_SIZE); > + current->nr_dirtied++; > } > } > EXPORT_SYMBOL(account_page_dirtied); > > -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- 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
