linux-kernel - [PATCH] Cgroup: Fix memory accounting scalability in shrink_page

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 19 Jul 2012 16:34:26 -0700
From:	Tim Chen <tim.c.chen@...ux.intel.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Mel Gorman <mel@....ul.ie>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Minchan Kim <minchan@...nel.org>,
	Johannes Weiner <hannes@...xchg.org>
Cc:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	"andi.kleen" <andi.kleen@...el.com>, linux-mm <linux-mm@...ck.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] Cgroup: Fix memory accounting scalability in
 shrink_page_list

Hi,

I noticed in a multi-process parallel files reading benchmark I ran on a
8 socket machine,  throughput slowed down by a factor of 8 when I ran
the benchmark within a cgroup container.  I traced the problem to the
following code path (see below) when we are trying to reclaim memory
from file cache.  The res_counter_uncharge function is called on every
page that's reclaimed and created heavy lock contention.  The patch
below allows the reclaimed pages to be uncharged from the resource
counter in batch and recovered the regression. 

Tim

     40.67%           usemem  [kernel.kallsyms]                   [k] _raw_spin_lock
                      |
                      --- _raw_spin_lock
                         |
                         |--92.61%-- res_counter_uncharge
                         |          |
                         |          |--100.00%-- __mem_cgroup_uncharge_common
                         |          |          |
                         |          |          |--100.00%-- mem_cgroup_uncharge_cache_page
                         |          |          |          __remove_mapping
                         |          |          |          shrink_page_list
                         |          |          |          shrink_inactive_list
                         |          |          |          shrink_mem_cgroup_zone
                         |          |          |          shrink_zone
                         |          |          |          do_try_to_free_pages
                         |          |          |          try_to_free_pages
                         |          |          |          __alloc_pages_nodemask
                         |          |          |          alloc_pages_current


---
Signed-off-by: Tim Chen <tim.c.chen@...ux.intel.com>
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 33dc256..aac5672 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -779,6 +779,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 
 	cond_resched();
 
+	mem_cgroup_uncharge_start();
 	while (!list_empty(page_list)) {
 		enum page_references references;
 		struct address_space *mapping;
@@ -1026,6 +1027,7 @@ keep_lumpy:
 
 	list_splice(&ret_pages, page_list);
 	count_vm_events(PGACTIVATE, pgactivate);
+	mem_cgroup_uncharge_end();
 	*ret_nr_dirty += nr_dirty;
 	*ret_nr_writeback += nr_writeback;
 	return nr_reclaimed;


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/