lkml.org 
[lkml]   [2008]   [Aug]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [RFC][PATCH -mm 0/7] memcg: lockless page_cgroup v1
On Wed, 20 Aug 2008 19:41:08 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:

> On Wed, 20 Aug 2008 18:53:06 +0900
> KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
>
> > Hi, this is a patch set for lockless page_cgroup.
> >
> > dropped patches related to mem+swap controller for easy review.
> > (I'm rewriting it, too.)
> >
> > Changes from current -mm is.
> > - page_cgroup->flags operations is set to be atomic.
> > - lock_page_cgroup() is removed.
> > - page->page_cgroup is changed from unsigned long to struct page_cgroup*
> > - page_cgroup is freed by RCU.
> > - For avoiding race, charge/uncharge against mm/memory.c::insert_page() is
> > omitted. This is ususally used for mapping device's page. (I think...)
> >
> > In my quick test, perfomance is improved a little. But the benefit of this
> > patch is to allow access page_cgroup without lock. I think this is good
> > for Yamamoto's Dirty page tracking for memcg.
> > For I/O tracking people, I added a header file for allowing access to
> > page_cgroup from out of memcontrol.c
> >
> > The base kernel is recent mmtom. Any comments are welcome.
> > This is still under test. I have to do long-run test before removing "RFC".
> >
> Known problem: force_emtpy is broken...so rmdir will struck into nightmare.
> It's because of patch 2/7.
> will be fixed in the next version.
>

This is a quick fix but I think I can find some better solution..
==
Because removal from LRU is delayed, mz->lru will never be empty until
someone kick drain. This patch rotate LRU while force_empty and makes
page_cgroup will be freed.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>


---
mm/memcontrol.c | 40 +++++++++++++++++++++++++---------------
1 file changed, 25 insertions(+), 15 deletions(-)

Index: mmtom-2.6.27-rc3+/mm/memcontrol.c
===================================================================
--- mmtom-2.6.27-rc3+.orig/mm/memcontrol.c
+++ mmtom-2.6.27-rc3+/mm/memcontrol.c
@@ -893,34 +893,45 @@ static void mem_cgroup_force_empty_list(
struct mem_cgroup_per_zone *mz,
enum lru_list lru)
{
- struct page_cgroup *pc;
+ struct page_cgroup *pc, *tmp;
struct page *page;
int count = FORCE_UNCHARGE_BATCH;
unsigned long flags;
struct list_head *list;
+ int drain, rotate;

list = &mz->lists[lru];

spin_lock_irqsave(&mz->lru_lock, flags);
+ rotate = 0;
while (!list_empty(list)) {
pc = list_entry(list->prev, struct page_cgroup, lru);
- page = pc->page;
- get_page(page);
- spin_unlock_irqrestore(&mz->lru_lock, flags);
- /*
- * Check if this page is on LRU. !LRU page can be found
- * if it's under page migration.
- */
- if (PageLRU(page)) {
- __mem_cgroup_uncharge_common(page,
- MEM_CGROUP_CHARGE_TYPE_FORCE);
- put_page(page);
+ drain = PcgObsolete(pc);
+ if (drain) {
+ /* Skip this */
+ list_move(&pc->lru);
+ spin_unlock_irqrestore(&mz->lru_lock, flags);
+ rotate++;
+ if (rotate > MEMCG_LRU_THRESH/2)
+ mem_cgroup_all_force_drain();
+ cond_resched();
+ } else {
+ page = pc->page;
+ get_page(page);
+ spin_unlock_irqrestore(&mz->lru_lock, flags);
+ /*
+ * Check if this page is on LRU. !LRU page can be found
+ * if it's under page migration.
+ */
+ if (PageLRU(page)) {
+ __mem_cgroup_uncharge_common(page,
+ MEM_CGROUP_CHARGE_TYPE_FORCE);
+ }
if (--count <= 0) {
count = FORCE_UNCHARGE_BATCH;
cond_resched();
}
- } else
- cond_resched();
+ }
spin_lock_irqsave(&mz->lru_lock, flags);
}
spin_unlock_irqrestore(&mz->lru_lock, flags);
@@ -954,7 +965,6 @@ static int mem_cgroup_force_empty(struct
}
}
ret = 0;
- mem_cgroup_all_force_drain();
out:
css_put(&mem->css);
return ret;



\
 
 \ /
  Last update: 2008-08-20 12:57    [W:0.122 / U:3.008 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site