[PATCH 6/6] [TCP]: Reorganize struct tcp_sock to save 16 bytes on 64-bit arch

2008-01-31 Thread Arnaldo Carvalho de Melo 
/home/acme/git/net-2.6/net/ipv6/tcp_ipv6.c:
  struct tcp_sock  |  -16
  struct tcp6_sock |  -16
 2 structs changed

Now it is at:

/* size: 1552, cachelines: 25 */
/* paddings: 2, sum paddings: 8 */
/* last cacheline: 16 bytes */

As soon as we stop using skb_queue_list we'll get it down to 24 cachelines.

Signed-off-by: Arnaldo Carvalho de Melo [EMAIL PROTECTED]
---
 include/linux/tcp.h |6 --
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 08027f1..f48644d 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -304,7 +304,6 @@ struct tcp_sock {
u32 rtt_seq;/* sequence number to update rttvar */
 
u32 packets_out;/* Packets which are in flight*/
-   u32 retrans_out;/* Retransmitted packets out*/
 /*
  *  Options received (usually on last packet, some only on SYN packets).
  */
@@ -332,6 +331,8 @@ struct tcp_sock {
 
struct tcp_sack_block recv_sack_cache[4];
 
+   u32 retrans_out;/* Retransmitted packets out*/
+
struct sk_buff *highest_sack;   /* highest skb with SACK received
 * (validity guaranteed only if
 * sacked_out  0)
@@ -372,7 +373,6 @@ struct tcp_sock {
 
unsigned intkeepalive_time;   /* time before keep alive 
takes place */
unsigned intkeepalive_intvl;  /* time interval between keep 
alive probes */
-   int linger2;
 
unsigned long last_synq_overflow; 
 
@@ -398,6 +398,8 @@ struct tcp_sock {
u32   probe_seq_end;
} mtu_probe;
 
+   int linger2;
+
 #ifdef CONFIG_TCP_MD5SIG
 /* TCP AF-Specific parts; only used by MD5 Signature support so far */
struct tcp_sock_af_ops  *af_specific;
-- 
1.5.3.8

-
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Re: [PATCH 6/6] [TCP]: Reorganize struct tcp_sock to save 16 bytes on 64-bit arch

2008-01-31 Thread Arnaldo Carvalho de Melo 
Em Thu, Jan 31, 2008 at 08:57:53PM +0100, Eric Dumazet escreveu:
 Arnaldo Carvalho de Melo a écrit :
 /home/acme/git/net-2.6/net/ipv6/tcp_ipv6.c:
   struct tcp_sock  |  -16
   struct tcp6_sock |  -16
  2 structs changed

 Now it is at:

 /* size: 1552, cachelines: 25 */
 /* paddings: 2, sum paddings: 8 */
 /* last cacheline: 16 bytes */

 As soon as we stop using skb_queue_list we'll get it down to 24 cachelines.

 Signed-off-by: Arnaldo Carvalho de Melo [EMAIL PROTECTED]
 ---
  include/linux/tcp.h |6 --
  1 files changed, 4 insertions(+), 2 deletions(-)

 diff --git a/include/linux/tcp.h b/include/linux/tcp.h
 index 08027f1..f48644d 100644
 --- a/include/linux/tcp.h
 +++ b/include/linux/tcp.h
 @@ -304,7 +304,6 @@ struct tcp_sock {
  u32 rtt_seq;/* sequence number to update rttvar */
  u32 packets_out;/* Packets which are in flight*/
 -u32 retrans_out;/* Retransmitted packets out*/
  /*
   *  Options received (usually on last packet, some only on SYN packets).
   */
 @@ -332,6 +331,8 @@ struct tcp_sock {
  struct tcp_sack_block recv_sack_cache[4];
  +   u32 retrans_out;/* Retransmitted packets out*/
 +

 Hum... retrans_out should sit close to packets_out (or lost_out/sacked_out 
 ???), please.

 'struct tcp_sock' is very large on 64 bits, so I would prefer to make sure 
 most paths dont need to touch all 24 cache lines (or 25 cache lines).

That is perfectly fine, I'll replace my patch with another, that states
this beyond doubt.

- Arnaldo
-
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