Messages in this thread | | | Date | Thu, 2 Feb 2012 14:39:26 +0400 | From | Glauber Costa <> | Subject | Re: [v3.3-rc2+ PATCH] tcp: properly initialize tcp memory limits |
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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<jasowang@redhat.com> Acked-by: Glauber Costa <glommer@parallels.com>
> --- > 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 <glommer@parallels.com>
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