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Date: Fri, 9 Sep 2011 11:47:20 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To: Glauber Costa <glommer@...allels.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
containers@...ts.osdl.org, netdev@...r.kernel.org,
xemul@...allels.com, "David S. Miller" <davem@...emloft.net>,
"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: Re: [PATCH v2 1/9] per-netns ipv4 sysctl_tcp_mem
On Wed, 7 Sep 2011 01:23:11 -0300
Glauber Costa <glommer@...allels.com> wrote:
> This patch allows each namespace to independently set up
> its levels for tcp memory pressure thresholds. This patch
> alone does not buy much: we need to make this values
> per group of process somehow. This is achieved in the
> patches that follows in this patchset.
>
> Signed-off-by: Glauber Costa <glommer@...allels.com>
> CC: David S. Miller <davem@...emloft.net>
> CC: Hiroyouki Kamezawa <kamezawa.hiroyu@...fujitsu.com>
> CC: Eric W. Biederman <ebiederm@...ssion.com>
Hmm, it may be better to post this patch as independent one.
I'm not familiar with this area...but try review ;)
> ---
> include/net/netns/ipv4.h | 1 +
> include/net/tcp.h | 1 -
> net/ipv4/sysctl_net_ipv4.c | 51 +++++++++++++++++++++++++++++++++++++------
> net/ipv4/tcp.c | 13 +++-------
> 4 files changed, 49 insertions(+), 17 deletions(-)
>
> diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
> index d786b4f..bbd023a 100644
> --- a/include/net/netns/ipv4.h
> +++ b/include/net/netns/ipv4.h
> @@ -55,6 +55,7 @@ struct netns_ipv4 {
> int current_rt_cache_rebuild_count;
>
> unsigned int sysctl_ping_group_range[2];
> + long sysctl_tcp_mem[3];
>
> atomic_t rt_genid;
> atomic_t dev_addr_genid;
Hmm, in original placement, sysctl_tcp_mem[] was on __read_mostly
area. Doesn't this placement cause many cache invalidations ?
> diff --git a/include/net/tcp.h b/include/net/tcp.h
> index 149a415..6bfdd9b 100644
> --- a/include/net/tcp.h
> +++ b/include/net/tcp.h
> @@ -230,7 +230,6 @@ extern int sysctl_tcp_fack;
> extern int sysctl_tcp_reordering;
> extern int sysctl_tcp_ecn;
> extern int sysctl_tcp_dsack;
> -extern long sysctl_tcp_mem[3];
> extern int sysctl_tcp_wmem[3];
> extern int sysctl_tcp_rmem[3];
> extern int sysctl_tcp_app_win;
> diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
> index 69fd720..0d74b9d 100644
> --- a/net/ipv4/sysctl_net_ipv4.c
> +++ b/net/ipv4/sysctl_net_ipv4.c
> @@ -14,6 +14,7 @@
> #include <linux/init.h>
> #include <linux/slab.h>
> #include <linux/nsproxy.h>
> +#include <linux/swap.h>
> #include <net/snmp.h>
> #include <net/icmp.h>
> #include <net/ip.h>
> @@ -174,6 +175,36 @@ static int proc_allowed_congestion_control(ctl_table *ctl,
> return ret;
> }
>
> +static int ipv4_tcp_mem(ctl_table *ctl, int write,
> + void __user *buffer, size_t *lenp,
> + loff_t *ppos)
> +{
> + int ret;
> + unsigned long vec[3];
> + struct net *net = current->nsproxy->net_ns;
> + int i;
> +
> + ctl_table tmp = {
> + .data = &vec,
> + .maxlen = sizeof(vec),
> + .mode = ctl->mode,
> + };
> +
> + if (!write) {
> + ctl->data = &net->ipv4.sysctl_tcp_mem;
> + return proc_doulongvec_minmax(ctl, write, buffer, lenp, ppos);
> + }
> +
> + ret = proc_doulongvec_minmax(&tmp, write, buffer, lenp, ppos);
> + if (ret)
> + return ret;
> +
> + for (i = 0; i < 3; i++)
> + net->ipv4.sysctl_tcp_mem[i] = vec[i];
> +
> + return 0;
> +}
> +
> static struct ctl_table ipv4_table[] = {
> {
> .procname = "tcp_timestamps",
> @@ -433,13 +464,6 @@ static struct ctl_table ipv4_table[] = {
> .proc_handler = proc_dointvec
> },
> {
> - .procname = "tcp_mem",
> - .data = &sysctl_tcp_mem,
> - .maxlen = sizeof(sysctl_tcp_mem),
> - .mode = 0644,
> - .proc_handler = proc_doulongvec_minmax
> - },
> - {
> .procname = "tcp_wmem",
> .data = &sysctl_tcp_wmem,
> .maxlen = sizeof(sysctl_tcp_wmem),
> @@ -721,6 +745,12 @@ static struct ctl_table ipv4_net_table[] = {
> .mode = 0644,
> .proc_handler = ipv4_ping_group_range,
> },
> + {
> + .procname = "tcp_mem",
> + .maxlen = sizeof(init_net.ipv4.sysctl_tcp_mem),
> + .mode = 0644,
> + .proc_handler = ipv4_tcp_mem,
> + },
> { }
> };
>
> @@ -734,6 +764,7 @@ EXPORT_SYMBOL_GPL(net_ipv4_ctl_path);
> static __net_init int ipv4_sysctl_init_net(struct net *net)
> {
> struct ctl_table *table;
> + unsigned long limit;
>
> table = ipv4_net_table;
> if (!net_eq(net, &init_net)) {
> @@ -769,6 +800,12 @@ static __net_init int ipv4_sysctl_init_net(struct net *net)
>
> net->ipv4.sysctl_rt_cache_rebuild_count = 4;
>
> + 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);
> if (net->ipv4.ipv4_hdr == NULL)
> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> index 46febca..f06df24 100644
> --- a/net/ipv4/tcp.c
> +++ b/net/ipv4/tcp.c
> @@ -266,6 +266,7 @@
> #include <linux/crypto.h>
> #include <linux/time.h>
> #include <linux/slab.h>
> +#include <linux/nsproxy.h>
>
> #include <net/icmp.h>
> #include <net/tcp.h>
> @@ -282,11 +283,9 @@ int sysctl_tcp_fin_timeout __read_mostly = TCP_FIN_TIMEOUT;
> struct percpu_counter tcp_orphan_count;
> EXPORT_SYMBOL_GPL(tcp_orphan_count);
>
> -long sysctl_tcp_mem[3] __read_mostly;
> int sysctl_tcp_wmem[3] __read_mostly;
> int sysctl_tcp_rmem[3] __read_mostly;
>
> -EXPORT_SYMBOL(sysctl_tcp_mem);
> EXPORT_SYMBOL(sysctl_tcp_rmem);
> EXPORT_SYMBOL(sysctl_tcp_wmem);
>
> @@ -3277,14 +3276,10 @@ void __init tcp_init(void)
> sysctl_tcp_max_orphans = cnt / 2;
> sysctl_max_syn_backlog = max(128, cnt / 256);
>
> - limit = nr_free_buffer_pages() / 8;
> - limit = max(limit, 128UL);
> - sysctl_tcp_mem[0] = limit / 4 * 3;
> - sysctl_tcp_mem[1] = limit;
> - sysctl_tcp_mem[2] = sysctl_tcp_mem[0] * 2;
> -
> /* Set per-socket limits to no more than 1/128 the pressure threshold */
> - limit = ((unsigned long)sysctl_tcp_mem[1]) << (PAGE_SHIFT - 7);
> + limit = (unsigned long)init_net.ipv4.sysctl_tcp_mem[1];
> + limit <<= (PAGE_SHIFT - 7);
> +
I'm not sure but...why defined as 'long' ?
BTW, when I grep,
tcp_input.c: atomic_long_read(&tcp_memory_allocated) < sysctl_tcp_mem[0])
tcp_input.c: if (atomic_long_read(&tcp_memory_allocated) >= sysctl_tcp_mem[0])
Don't you need to change this ?
Thanks,
-Kame
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