netdev - [PATCH v2] tcp: restore correct limit

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Message-ID: <1334055402.3126.87.camel@edumazet-glaptop>
Date:	Tue, 10 Apr 2012 12:56:42 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Jason Wang <jasowang@...hat.com>
Cc:	monstr@...str.eu, netdev@...r.kernel.org,
	John Williams <john.williams@...alogix.com>,
	David Miller <davem@...emloft.net>,
	Glauber Costa <glommer@...allels.com>
Subject: [PATCH v2] tcp: restore correct limit

Commit c43b874d5d714f (tcp: properly initialize tcp memory limits) tried
to fix a regression added in commits 4acb4190 & 3dc43e3,
but still get it wrong.

Result is machines with low amount of memory have too small tcp_rmem[2]
value and slow tcp receives : Per socket limit being 1/1024 of memory
instead of 1/128 in old kernels, so rcv window is capped to small
values.

Fix this to match comment and previous behavior.

Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
Cc: Jason Wang <jasowang@...hat.com>
Cc: Glauber Costa <glommer@...allels.com>
---
v2: remove one useless "limit = max(limit, 128UL);" line

 net/ipv4/tcp.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 5d54ed3..7758a83 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3302,8 +3302,7 @@ void __init tcp_init(void)
 
 	tcp_init_mem(&init_net);
 	/* 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);
+	limit = nr_free_buffer_pages() << (PAGE_SHIFT - 7);
 	max_share = min(4UL*1024*1024, limit);
 
 	sysctl_tcp_wmem[0] = SK_MEM_QUANTUM;


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