From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755535Ab2BBKkZ (ORCPT ); Thu, 2 Feb 2012 05:40:25 -0500 Received: from mx2.parallels.com ([64.131.90.16]:35192 "EHLO mx2.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754822Ab2BBKkY (ORCPT ); Thu, 2 Feb 2012 05:40:24 -0500 Message-ID: <4F2A67DE.1000909@parallels.com> Date: Thu, 2 Feb 2012 14:39:26 +0400 From: Glauber Costa User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:9.0) Gecko/20111222 Thunderbird/9.0 MIME-Version: 1.0 To: Jason Wang CC: , , , Subject: Re: [v3.3-rc2+ PATCH] tcp: properly initialize tcp memory limits References: <20120202100700.38694.80000.stgit@amd-6168-8-1.englab.nay.redhat.com> In-Reply-To: <20120202100700.38694.80000.stgit@amd-6168-8-1.englab.nay.redhat.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/02/2012 02:07 PM, Jason Wang wrote: > Commit 4acb4190 tries to fix the using uninitialized value > introduced by commit 3dc43e3, but it would make the > per-socket memory limits too small. > > This patch fixes this and also remove the redundant codes > introduced in 4acb4190. > > Signed-off-by: Jason Wang Acked-by: Glauber Costa > --- > net/ipv4/sysctl_net_ipv4.c | 5 ----- > net/ipv4/tcp.c | 4 ++-- > 2 files changed, 2 insertions(+), 7 deletions(-) > > diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c > index 4cb9cd2..1eb8caa 100644 > --- a/net/ipv4/sysctl_net_ipv4.c > +++ b/net/ipv4/sysctl_net_ipv4.c > @@ -815,11 +815,6 @@ static __net_init int ipv4_sysctl_init_net(struct net *net) > net->ipv4.sysctl_rt_cache_rebuild_count = 4; > > tcp_init_mem(net); > - limit = nr_free_buffer_pages() / 8; > - limit = max(limit, 128UL); > - net->ipv4.sysctl_tcp_mem[0] = limit / 4 * 3; > - net->ipv4.sysctl_tcp_mem[1] = limit; > - net->ipv4.sysctl_tcp_mem[2] = net->ipv4.sysctl_tcp_mem[0] * 2; > > net->ipv4.ipv4_hdr = register_net_sysctl_table(net, > net_ipv4_ctl_path, table); Ok, this is indeed a good change, since we avoid initializing it twice. > diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c > index 06373b4..3a7514b 100644 > --- a/net/ipv4/tcp.c > +++ b/net/ipv4/tcp.c > @@ -3218,7 +3218,6 @@ __setup("thash_entries=", set_thash_entries); > > void tcp_init_mem(struct net *net) > { > - /* Set per-socket limits to no more than 1/128 the pressure threshold */ > unsigned long limit = nr_free_buffer_pages() / 8; > limit = max(limit, 128UL); > net->ipv4.sysctl_tcp_mem[0] = limit / 4 * 3; > @@ -3287,7 +3286,8 @@ void __init tcp_init(void) > sysctl_max_syn_backlog = max(128, cnt / 256); > > tcp_init_mem(&init_net); > - limit = nr_free_buffer_pages() / 8; > + /* Set per-socket limits to no more than 1/128 the pressure threshold */ > + limit = nr_free_buffer_pages()<< (PAGE_SHIFT - 10); > limit = max(limit, 128UL); > max_share = min(4UL*1024*1024, limit); Indeed, this ends up influencing the value of max_share used below to initialize the other fields. I like your change because now the limit variable is being set independently between the global (now per-cgroup) and the per-socket limits. (it previously was limit = sysctl_tcp_mem[1] << (PAGE_SHIFT-7)) So in the end, I personally think this is even clearer than what we had before. Acked-by: Glauber Costa