Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751392AbZL1Clz (ORCPT ); Sun, 27 Dec 2009 21:41:55 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751145AbZL1Cly (ORCPT ); Sun, 27 Dec 2009 21:41:54 -0500 Received: from TYO201.gate.nec.co.jp ([202.32.8.193]:42232 "EHLO tyo201.gate.nec.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751131AbZL1Clx (ORCPT ); Sun, 27 Dec 2009 21:41:53 -0500 Date: Mon, 28 Dec 2009 11:37:39 +0900 From: Daisuke Nishimura To: "Kirill A. Shutemov" Cc: containers@lists.linux-foundation.org, linux-mm@kvack.org, Paul Menage , Li Zefan , Andrew Morton , KAMEZAWA Hiroyuki , Balbir Singh , Pavel Emelyanov , Dan Malek , Vladislav Buzov , Alexander Shishkin , linux-kernel@vger.kernel.org, Daisuke Nishimura Subject: Re: [PATCH v4 3/4] memcg: rework usage of stats by soft limit Message-Id: <20091228113739.3c38fd78.nishimura@mxp.nes.nec.co.jp> In-Reply-To: References: <3f29ccc3c93e2defd70fc1c4ca8c133908b70b0b.1261858972.git.kirill@shutemov.name> <59a7f92356bf1508f06d12c501a7aa4feffb1bbc.1261858972.git.kirill@shutemov.name> Organization: NEC Soft, Ltd. X-Mailer: Sylpheed 2.6.0 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3221 Lines: 83 On Sun, 27 Dec 2009 04:09:01 +0200, "Kirill A. Shutemov" wrote: > Instead of incrementing counter on each page in/out and comparing it > with constant, we set counter to constant, decrement counter on each > page in/out and compare it with zero. We want to make comparing as fast > as possible. On many RISC systems (probably not only RISC) comparing > with zero is more effective than comparing with a constant, since not > every constant can be immediate operand for compare instruction. > > Also, I've renamed MEM_CGROUP_STAT_EVENTS to MEM_CGROUP_STAT_SOFTLIMIT, > since really it's not a generic counter. > > Signed-off-by: Kirill A. Shutemov > --- > mm/memcontrol.c | 19 ++++++++++++++----- > 1 files changed, 14 insertions(+), 5 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 1d71cb4..36eb7af 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -69,8 +69,9 @@ enum mem_cgroup_stat_index { > MEM_CGROUP_STAT_FILE_MAPPED, /* # of pages charged as file rss */ > MEM_CGROUP_STAT_PGPGIN_COUNT, /* # of pages paged in */ > MEM_CGROUP_STAT_PGPGOUT_COUNT, /* # of pages paged out */ > - MEM_CGROUP_STAT_EVENTS, /* sum of pagein + pageout for internal use */ > MEM_CGROUP_STAT_SWAPOUT, /* # of pages, swapped out */ > + MEM_CGROUP_STAT_SOFTLIMIT, /* decrements on each page in/out. > + used by soft limit implementation */ > > MEM_CGROUP_STAT_NSTATS, > }; > @@ -90,6 +91,13 @@ __mem_cgroup_stat_reset_safe(struct mem_cgroup_stat_cpu *stat, > stat->count[idx] = 0; > } > > +static inline void > +__mem_cgroup_stat_set(struct mem_cgroup_stat_cpu *stat, > + enum mem_cgroup_stat_index idx, s64 val) > +{ > + stat->count[idx] = val; > +} > + I think it would be better to name it __mem_cgroup_stat_set_safe. And could you remove the definition of __mem_cgroup_stat_reset ? Thanks, Daisuke Nishimura. > static inline s64 > __mem_cgroup_stat_read_local(struct mem_cgroup_stat_cpu *stat, > enum mem_cgroup_stat_index idx) > @@ -380,9 +388,10 @@ static bool mem_cgroup_soft_limit_check(struct mem_cgroup *mem) > > cpu = get_cpu(); > cpustat = &mem->stat.cpustat[cpu]; > - val = __mem_cgroup_stat_read_local(cpustat, MEM_CGROUP_STAT_EVENTS); > - if (unlikely(val > SOFTLIMIT_EVENTS_THRESH)) { > - __mem_cgroup_stat_reset_safe(cpustat, MEM_CGROUP_STAT_EVENTS); > + val = __mem_cgroup_stat_read_local(cpustat, MEM_CGROUP_STAT_SOFTLIMIT); > + if (unlikely(val < 0)) { > + __mem_cgroup_stat_set(cpustat, MEM_CGROUP_STAT_SOFTLIMIT, > + SOFTLIMIT_EVENTS_THRESH); > ret = true; > } > put_cpu(); > @@ -515,7 +524,7 @@ static void mem_cgroup_charge_statistics(struct mem_cgroup *mem, > else > __mem_cgroup_stat_add_safe(cpustat, > MEM_CGROUP_STAT_PGPGOUT_COUNT, 1); > - __mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_EVENTS, 1); > + __mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_SOFTLIMIT, -1); > put_cpu(); > } > > -- > 1.6.5.7 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/