On Tue, Feb 22, 2011 at 07:07:19PM -0500, Vivek Goyal wrote: > On Wed, Feb 23, 2011 at 12:05:34AM +0100, Andrea Righi wrote: > > On Tue, Feb 22, 2011 at 04:00:30PM -0500, Vivek Goyal wrote: > > > On Tue, Feb 22, 2011 at 06:12:55PM +0100, Andrea Righi wrote: > > > > Add the tracking of buffered (writeback) and anonymous pages. > > > > > > > > Dirty pages in the page cache can be processed asynchronously by the > > > > per-bdi flusher kernel threads or by any other thread in the system, > > > > according to the writeback policy. > > > > > > > > For this reason the real writes to the underlying block devices may > > > > occur in a different IO context respect to the task that originally > > > > generated the dirty pages involved in the IO operation. This makes > > > > the tracking and throttling of writeback IO more complicate respect to > > > > the synchronous IO from the blkio controller's point of view. > > > > > > > > The idea is to save the cgroup owner of each anonymous page and dirty > > > > page in page cache. A page is associated to a cgroup the first time it > > > > is dirtied in memory (for file cache pages) or when it is set as > > > > swap-backed (for anonymous pages). This information is stored using the > > > > page_cgroup functionality. > > > > > > > > Then, at the block layer, it is possible to retrieve the throttle group > > > > looking at the bio_page(bio). If the page was not explicitly associated > > > > to any cgroup the IO operation is charged to the current task/cgroup, as > > > > it was done by the previous implementation. > > > > > > > > Signed-off-by: Andrea Righi <arighi@xxxxxxxxxxx> > > > > --- > > > > block/blk-throttle.c | 87 +++++++++++++++++++++++++++++++++++++++++++++++- > > > > include/linux/blkdev.h | 26 ++++++++++++++- > > > > 2 files changed, 111 insertions(+), 2 deletions(-) > > > > > > > > diff --git a/block/blk-throttle.c b/block/blk-throttle.c > > > > index 9ad3d1e..a50ee04 100644 > > > > --- a/block/blk-throttle.c > > > > +++ b/block/blk-throttle.c > > > > @@ -8,6 +8,10 @@ > > > > #include <linux/slab.h> > > > > #include <linux/blkdev.h> > > > > #include <linux/bio.h> > > > > +#include <linux/memcontrol.h> > > > > +#include <linux/mm_inline.h> > > > > +#include <linux/pagemap.h> > > > > +#include <linux/page_cgroup.h> > > > > #include <linux/blktrace_api.h> > > > > #include <linux/blk-cgroup.h> > > > > > > > > @@ -221,6 +225,85 @@ done: > > > > return tg; > > > > } > > > > > > > > +static inline bool is_kernel_io(void) > > > > +{ > > > > + return !!(current->flags & (PF_KTHREAD | PF_KSWAPD | PF_MEMALLOC)); > > > > +} > > > > + > > > > +static int throtl_set_page_owner(struct page *page, struct mm_struct *mm) > > > > +{ > > > > + struct blkio_cgroup *blkcg; > > > > + unsigned short id = 0; > > > > + > > > > + if (blkio_cgroup_disabled()) > > > > + return 0; > > > > + if (!mm) > > > > + goto out; > > > > + rcu_read_lock(); > > > > + blkcg = task_to_blkio_cgroup(rcu_dereference(mm->owner)); > > > > + if (likely(blkcg)) > > > > + id = css_id(&blkcg->css); > > > > + rcu_read_unlock(); > > > > +out: > > > > + return page_cgroup_set_owner(page, id); > > > > +} > > > > + > > > > +int blk_throtl_set_anonpage_owner(struct page *page, struct mm_struct *mm) > > > > +{ > > > > + return throtl_set_page_owner(page, mm); > > > > +} > > > > +EXPORT_SYMBOL(blk_throtl_set_anonpage_owner); > > > > + > > > > +int blk_throtl_set_filepage_owner(struct page *page, struct mm_struct *mm) > > > > +{ > > > > + if (is_kernel_io() || !page_is_file_cache(page)) > > > > + return 0; > > > > + return throtl_set_page_owner(page, mm); > > > > +} > > > > +EXPORT_SYMBOL(blk_throtl_set_filepage_owner); > > > > > > Why are we exporting all these symbols? > > > > Right. Probably a single one is enough: > > > > int blk_throtl_set_page_owner(struct page *page, > > struct mm_struct *mm, bool anon); > > Who is going to use this single export? Which module? > I was actually thinking at some filesystem modules, but I was wrong, because at the moment no one needs the export. I'll remove it in the next version of the patch. Thanks, -Andrea -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>