linux-kernel - Re: [PATCH 5/6] memcg: optimize memcg_get_hierarchical

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 for Android: free password hash cracker in your pocket

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

Message-ID: <20120623093934.GN27816@cmpxchg.org>
Date:	Sat, 23 Jun 2012 11:39:34 +0200
From:	Johannes Weiner <hannes@...xchg.org>
To:	Wanpeng Li <liwp.linux@...il.com>
Cc:	linux-mm@...ck.org, Michal Hocko <mhocko@...e.cz>,
	Balbir Singh <bsingharora@...il.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Mel Gorman <mel@....ul.ie>, Minchan Kim <minchan@...nel.org>,
	linux-kernel@...r.kernel.org, cgroups@...r.kernel.org,
	Gavin Shan <shangw@...ux.vnet.ibm.com>
Subject: Re: [PATCH 5/6] memcg: optimize memcg_get_hierarchical_limit

On Sat, Jun 23, 2012 at 02:18:17PM +0800, Wanpeng Li wrote:
> From: Wanpeng Li <liwp@...ux.vnet.ibm.com>
> 
> Optimize memcg_get_hierarchical_limit to save cpu cycle.
> 
> Signed-off-by: Wanpeng Li <liwp.linux@...il.com>

I really would have thought the compiler would detect it, but this
patch actually does switch around move and jump.

But this is miniscule and anything but a fastpath...

> ---
>  mm/memcontrol.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index c821e36..1ca79e2 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -3917,9 +3917,9 @@ static void memcg_get_hierarchical_limit(struct mem_cgroup *memcg,
>  
>  	min_limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
>  	min_memsw_limit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
> -	cgroup = memcg->css.cgroup;
>  	if (!memcg->use_hierarchy)
>  		goto out;
> +	cgroup = memcg->css.cgroup;
>  
>  	while (cgroup->parent) {
>  		cgroup = cgroup->parent;
> -- 
> 1.7.9.5
> 
--
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/