1 files changed, 124 insertions, 0 deletions

diff --git a/recipes-kernel/linux/linux-ti33x-psp-3.2/3.2.18/0019-tcp-change-tcp_adv_win_scale-and-tcp_rmem-2.patch b/recipes-kernel/linux/linux-ti33x-psp-3.2/3.2.18/0019-tcp-change-tcp_adv_win_scale-and-tcp_rmem-2.patch
new file mode 100644
index 00000000..e0e1dda9
--- /dev/null
+++ b/recipes-kernel/linux/linux-ti33x-psp-3.2/3.2.18/0019-tcp-change-tcp_adv_win_scale-and-tcp_rmem-2.patch
@@ -0,0 +1,124 @@
+From 98d841428279a8060b46cf13a1463ebbeca65b4a Mon Sep 17 00:00:00 2001
+From: Eric Dumazet <edumazet@google.com>
+Date: Wed, 2 May 2012 02:28:41 +0000
+Subject: [PATCH 19/56] tcp: change tcp_adv_win_scale and tcp_rmem[2]
+
+[ Upstream commit b49960a05e32121d29316cfdf653894b88ac9190 ]
+
+tcp_adv_win_scale default value is 2, meaning we expect a good citizen
+skb to have skb->len / skb->truesize ratio of 75% (3/4)
+
+In 2.6 kernels we (mis)accounted for typical MSS=1460 frame :
+1536 + 64 + 256 = 1856 'estimated truesize', and 1856 * 3/4 = 1392.
+So these skbs were considered as not bloated.
+
+With recent truesize fixes, a typical MSS=1460 frame truesize is now the
+more precise :
+2048 + 256 = 2304. But 2304 * 3/4 = 1728.
+So these skb are not good citizen anymore, because 1460 < 1728
+
+(GRO can escape this problem because it build skbs with a too low
+truesize.)
+
+This also means tcp advertises a too optimistic window for a given
+allocated rcvspace : When receiving frames, sk_rmem_alloc can hit
+sk_rcvbuf limit and we call tcp_prune_queue()/tcp_collapse() too often,
+especially when application is slow to drain its receive queue or in
+case of losses (netperf is fast, scp is slow). This is a major latency
+source.
+
+We should adjust the len/truesize ratio to 50% instead of 75%
+
+This patch :
+
+1) changes tcp_adv_win_scale default to 1 instead of 2
+
+2) increase tcp_rmem[2] limit from 4MB to 6MB to take into account
+better truesize tracking and to allow autotuning tcp receive window to
+reach same value than before. Note that same amount of kernel memory is
+consumed compared to 2.6 kernels.
+
+Signed-off-by: Eric Dumazet <edumazet@google.com>
+Cc: Neal Cardwell <ncardwell@google.com>
+Cc: Tom Herbert <therbert@google.com>
+Cc: Yuchung Cheng <ycheng@google.com>
+Acked-by: Neal Cardwell <ncardwell@google.com>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
+---
+ Documentation/networking/ip-sysctl.txt |    4 ++--
+ net/ipv4/tcp.c                         |    9 +++++----
+ net/ipv4/tcp_input.c                   |    2 +-
+ 3 files changed, 8 insertions(+), 7 deletions(-)
+
+diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
+index 589f2da..a4399f5 100644
+--- a/Documentation/networking/ip-sysctl.txt
++++ b/Documentation/networking/ip-sysctl.txt
+@@ -137,7 +137,7 @@ tcp_adv_win_scale - INTEGER
+        (if tcp_adv_win_scale > 0) or bytes-bytes/2^(-tcp_adv_win_scale),
+        if it is <= 0.
+        Possible values are [-31, 31], inclusive.
+-       Default: 2
++       Default: 1
+ 
+ tcp_allowed_congestion_control - STRING
+        Show/set the congestion control choices available to non-privileged
+@@ -397,7 +397,7 @@ tcp_rmem - vector of 3 INTEGERs: min, default, max
+        net.core.rmem_max.  Calling setsockopt() with SO_RCVBUF disables
+        automatic tuning of that socket's receive buffer size, in which
+        case this value is ignored.
+-       Default: between 87380B and 4MB, depending on RAM size.
++       Default: between 87380B and 6MB, depending on RAM size.
+ 
+ tcp_sack - BOOLEAN
+        Enable select acknowledgments (SACKS).
+diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
+index 7904db4..8f826b1 100644
+--- a/net/ipv4/tcp.c
++++ b/net/ipv4/tcp.c
+@@ -3216,7 +3216,7 @@ void __init tcp_init(void)
+ {
+        struct sk_buff *skb = NULL;
+        unsigned long limit;
+-       int i, max_share, cnt;
++       int i, max_rshare, max_wshare, cnt;
+        unsigned long jiffy = jiffies;
+ 
+        BUILD_BUG_ON(sizeof(struct tcp_skb_cb) > sizeof(skb->cb));
+@@ -3280,15 +3280,16 @@ void __init tcp_init(void)
+ 
+        /* Set per-socket limits to no more than 1/128 the pressure threshold */
+        limit = ((unsigned long)sysctl_tcp_mem[1]) << (PAGE_SHIFT - 7);
+-       max_share = min(4UL*1024*1024, limit);
++       max_wshare = min(4UL*1024*1024, limit);
++       max_rshare = min(6UL*1024*1024, limit);
+ 
+        sysctl_tcp_wmem[0] = SK_MEM_QUANTUM;
+        sysctl_tcp_wmem[1] = 16*1024;
+-       sysctl_tcp_wmem[2] = max(64*1024, max_share);
++       sysctl_tcp_wmem[2] = max(64*1024, max_wshare);
+ 
+        sysctl_tcp_rmem[0] = SK_MEM_QUANTUM;
+        sysctl_tcp_rmem[1] = 87380;
+-       sysctl_tcp_rmem[2] = max(87380, max_share);
++       sysctl_tcp_rmem[2] = max(87380, max_rshare);
+ 
+        printk(KERN_INFO "TCP: Hash tables configured "
+               "(established %u bind %u)\n",
+diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
+index db07c9e..9726927 100644
+--- a/net/ipv4/tcp_input.c
++++ b/net/ipv4/tcp_input.c
+@@ -83,7 +83,7 @@ int sysctl_tcp_ecn __read_mostly = 2;
+ EXPORT_SYMBOL(sysctl_tcp_ecn);
+ int sysctl_tcp_dsack __read_mostly = 1;
+ int sysctl_tcp_app_win __read_mostly = 31;
+-int sysctl_tcp_adv_win_scale __read_mostly = 2;
++int sysctl_tcp_adv_win_scale __read_mostly = 1;
+ EXPORT_SYMBOL(sysctl_tcp_adv_win_scale);
+ 
+ int sysctl_tcp_stdurg __read_mostly;
+-- 
+1.7.7.6
+