From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fengguang Wu Subject: [net/loopback] +46% netperf.Throughput_Mbps Date: Fri, 24 Jan 2014 20:24:42 +0800 Message-ID: <20140124122442.GA27801@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org To: Eric Dumazet Return-path: Received: from mga02.intel.com ([134.134.136.20]:16254 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752167AbaAXMYo (ORCPT ); Fri, 24 Jan 2014 07:24:44 -0500 Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-ID: Hi Eric, Just FYI, we do measured +46.4% performance boost in netperf TCP_SENDFILE tests on an atom server for commit: commit 0cf833aefaa85bbfce3ff70485e5534e09254773 Author: Eric Dumazet AuthorDate: Sun Sep 23 22:28:59 2012 +0000 Commit: David S. Miller CommitDate: Mon Sep 24 16:23:53 2012 -0400 net: loopback: set default mtu to 64K loopback current mtu of 16436 bytes allows no more than 3 MSS TCP segments per frame, or 48 Kbytes. Changing mtu to 64K allows TCP stack to build large frames and significantly reduces stack overhead. Performance boost on bulk TCP transferts can be up to 30 %, partly because we now have one ACK message for two 64KB segments, and a lower probability of hitting /proc/sys/net/ipv4/tcp_reordering default limit. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller drivers/net/loopback.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) 2a6c8c7998f95b1 0cf833aefaa85bbfce3ff7048 --------------- ------------------------- 1233 ~ 4% +46.4% 1805 ~ 0% netperf.Throughput_Mbps 29214 ~ 9% -85.2% 4310 ~17% interrupts.RES 450970 ~ 3% -57.3% 192675 ~ 1% proc-vmstat.pgalloc_normal 453096 ~ 3% -57.0% 194790 ~ 1% proc-vmstat.pgfree 4664799 ~ 6% -47.7% 2441398 ~ 0% softirqs.NET_RX 1107 ~ 9% +62.2% 1797 ~ 0% slabinfo.kmalloc-1024.active_objs 1185 ~ 8% +54.2% 1827 ~ 0% slabinfo.kmalloc-1024.num_objs 244825 ~ 3% -28.6% 174791 ~ 0% proc-vmstat.numa_hit 244825 ~ 3% -28.6% 174791 ~ 0% proc-vmstat.numa_local 913 ~ 2% +39.3% 1271 ~ 1% slabinfo.skbuff_fclone_cache.active_objs 944 ~ 3% +36.9% 1293 ~ 1% slabinfo.skbuff_fclone_cache.num_objs 10 ~ 0% -10.0% 9 ~ 0% vmstat.procs.r 59630 ~12% -94.4% 3336 ~ 8% vmstat.system.cs 1233 ~ 1% -16.4% 1031 ~ 0% vmstat.system.in netperf.Throughput_Mbps 2000 ++------------------------------------------------------------------+ 1800 O+O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O | | 1600 ++ | 1400 ++ *. | *.*.*.. .*.*. + * *.*.*.*. .*.*. .*.* | 1200 ++ *.* *..* : : *.*. * | 1000 ++ : : | 800 ++ : : | | : : | 600 ++ : : | 400 ++ : : | | : : | 200 ++ : : | 0 ++----------------------*-*-----------------------------------------+