From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932418AbcA0NWE (ORCPT ); Wed, 27 Jan 2016 08:22:04 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:46901 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932176AbcA0NV7 (ORCPT ); Wed, 27 Jan 2016 08:21:59 -0500 From: Hans Westgaard Ry Cc: Hans Westgaard Ry , "David S. Miller" , Alexey Kuznetsov , James Morris , Hideaki YOSHIFUJI , Patrick McHardy , "\"\"hannes@stressinduktion.org\"\"" , netdev@vger.kernel.org (open list:NETWORKING [GENERAL]), linux-kernel@vger.kernel.org (open list), "Haakon Bugge" Subject: [PATCH v2] net:Add sysctl_tcp_sg_max_skb_frags Date: Wed, 27 Jan 2016 14:20:29 +0100 Message-Id: <1453900829-3384-1-git-send-email-hans.westgaard.ry@oracle.com> X-Mailer: git-send-email 2.4.3 In-Reply-To: <568F87AC.60405@oracle.com> References: <568F87AC.60405@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Source-IP: userv0022.oracle.com [156.151.31.74] To: unlisted-recipients:; (no To-header on input) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Devices may have limits on the number of fragments in an skb they support. Current codebase uses a constant as maximum for number of fragments one skb can hold and use. When enabling scatter/gather and running traffic with many small messages the codebase uses the maximum number of fragments and may thereby violate the max for certain devices. The patch introduces a global variable as max number of fragments in scatter/gather. Signed-off-by: Hans Westgaard Ry Reviewed-by: Håkon Bugge --- include/net/tcp.h | 2 ++ net/ipv4/sysctl_net_ipv4.c | 10 ++++++++++ net/ipv4/tcp.c | 8 +++++--- 3 files changed, 17 insertions(+), 3 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index f80e74c..8d18df3 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -285,6 +285,8 @@ extern int sysctl_tcp_invalid_ratelimit; extern int sysctl_tcp_pacing_ss_ratio; extern int sysctl_tcp_pacing_ca_ratio; +extern int sysctl_tcp_sg_max_skb_frags; + extern atomic_long_t tcp_memory_allocated; extern struct percpu_counter tcp_sockets_allocated; extern int tcp_memory_pressure; diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c index a0bd7a5..498dcf9 100644 --- a/net/ipv4/sysctl_net_ipv4.c +++ b/net/ipv4/sysctl_net_ipv4.c @@ -40,6 +40,7 @@ static int ip_ttl_min = 1; static int ip_ttl_max = 255; static int tcp_syn_retries_min = 1; static int tcp_syn_retries_max = MAX_TCP_SYNCNT; +static int tcp_sg_max_skb_frags = MAX_SKB_FRAGS; static int ip_ping_group_range_min[] = { 0, 0 }; static int ip_ping_group_range_max[] = { GID_T_MAX, GID_T_MAX }; @@ -761,6 +762,15 @@ static struct ctl_table ipv4_table[] = { .proc_handler = proc_dointvec_ms_jiffies, }, { + .procname = "tcp_sg_max_skb_frags", + .data = &sysctl_tcp_sg_max_skb_frags, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &one, + .extra2 = &tcp_sg_max_skb_frags, + }, + { .procname = "icmp_msgs_per_sec", .data = &sysctl_icmp_msgs_per_sec, .maxlen = sizeof(int), diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index c82cca1..928d2c7 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -300,7 +300,9 @@ EXPORT_SYMBOL(sysctl_tcp_wmem); atomic_long_t tcp_memory_allocated; /* Current allocated memory. */ EXPORT_SYMBOL(tcp_memory_allocated); - +/* maximum number of fragments for tcp scatter/gather */ +int sysctl_tcp_sg_max_skb_frags __read_mostly = MAX_SKB_FRAGS; +EXPORT_SYMBOL(sysctl_tcp_sg_max_skb_frags); /* * Current number of TCP sockets. */ @@ -938,7 +940,7 @@ new_segment: i = skb_shinfo(skb)->nr_frags; can_coalesce = skb_can_coalesce(skb, i, page, offset); - if (!can_coalesce && i >= MAX_SKB_FRAGS) { + if (!can_coalesce && i >= sysctl_tcp_sg_max_skb_frags) { tcp_mark_push(tp, skb); goto new_segment; } @@ -1211,7 +1213,7 @@ new_segment: if (!skb_can_coalesce(skb, i, pfrag->page, pfrag->offset)) { - if (i == MAX_SKB_FRAGS || !sg) { + if (i == sysctl_tcp_sg_max_skb_frags || !sg) { tcp_mark_push(tp, skb); goto new_segment; } -- 2.4.3