based on a clean up patch I sent.
==
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Coalessing multiple css_get() to a __css_get(count) as res_counter does.
This reduces memcg's cost, cache ping-pong very much.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
---
mm/memcontrol.c | 35 ++++++++++++++++++++++++++++-------
1 file changed, 28 insertions(+), 7 deletions(-)
Index: mmotm-2.6.34-May21/mm/memcontrol.c
===================================================================
--- mmotm-2.6.34-May21.orig/mm/memcontrol.c
+++ mmotm-2.6.34-May21/mm/memcontrol.c
@@ -1542,6 +1542,7 @@ static void drain_stock(struct memcg_sto
res_counter_uncharge(&old->res, stock->charge);
if (do_swap_account)
res_counter_uncharge(&old->memsw, stock->charge);
+ __css_put(&old->css, stock->charge/PAGE_SIZE);
}
stock->cached = NULL;
stock->charge = 0;
@@ -1570,6 +1571,7 @@ static void refill_stock(struct mem_cgro
stock->cached = mem;
}
stock->charge += val;
+ __css_get(&mem->css, val/PAGE_SIZE);
put_cpu_var(memcg_stock);
}
@@ -1710,6 +1712,7 @@ static int __mem_cgroup_try_charge(struc
* in system level. So, allow to go ahead dying process in addition to
* MEMDIE process.
*/
+again:
if (unlikely(test_thread_flag(TIF_MEMDIE)
|| fatal_signal_pending(current)))
goto bypass;
@@ -1720,25 +1723,42 @@ static int __mem_cgroup_try_charge(struc
* thread group leader migrates. It's possible that mm is not
* set, if so charge the init_mm (happens for pagecache usage).
*/
+
+ rcu_read_lock();
if (*memcg) {
mem = *memcg;
- css_get(&mem->css);
} else {
- mem = try_get_mem_cgroup_from_mm(mm);
+ mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
if (unlikely(!mem))
return 0;
*memcg = mem;
}
- VM_BUG_ON(css_is_removed(&mem->css));
- if (mem_cgroup_is_root(mem))
+ /* racy ? (but seems to never happen in usual */
+ if (unlikely(css_is_removed(&mem->css))) {
+ rcu_read_unlock();
+ mem = NULL;
+ goto bypass;
+ }
+
+ if (mem_cgroup_is_root(mem)) {
+ rcu_read_unlock();
goto done;
+ }
+ if (consume_stock(mem)) {
+ rcu_read_unlock();
+ goto done;
+ }
+ if (!css_tryget(&mem->css)) {
+ rcu_read_unlock();
+ goto again;
+ }
+ rcu_read_unlock();
+ /* Enter memory reclaim loop */
do {
bool oom_check;
- if (consume_stock(mem))
- goto done; /* don't need to fill stock */
/* If killed, bypass charge */
if (fatal_signal_pending(current))
goto bypass;
@@ -1756,7 +1776,8 @@ static int __mem_cgroup_try_charge(struc
break;
case CHARGE_RETRY: /* not in OOM situation but retry */
csize = PAGE_SIZE;
- break;
+ css_put(&mem->css);
+ goto again;
case CHARGE_WOULDBLOCK: /* !__GFP_WAIT */
goto nomem;
case CHARGE_NOMEM: /* OOM routine works */
--
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