From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH net-next] tcp: avoid expensive pskb_expand_head() calls Date: Wed, 18 Apr 2012 19:40:48 +0200 Message-ID: <1334770848.2472.314.camel@edumazet-glaptop> References: <1334653608.6226.11.camel@edumazet-laptop> <1334654187.2696.2.camel@jtkirshe-mobl> <4F8D93E1.9090000@intel.com> <1334681204.2472.41.camel@edumazet-glaptop> <1334698722.2472.71.camel@edumazet-glaptop> <1334764184.2472.299.camel@edumazet-glaptop> <4F8EF317.10504@hp.com> <1334769375.2472.310.camel@edumazet-glaptop> <4F8EFA24.8020909@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: netdev To: Rick Jones Return-path: Received: from mail-bk0-f46.google.com ([209.85.214.46]:48602 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751456Ab2DRRkz (ORCPT ); Wed, 18 Apr 2012 13:40:55 -0400 Received: by bkcik5 with SMTP id ik5so5705818bkc.19 for ; Wed, 18 Apr 2012 10:40:54 -0700 (PDT) In-Reply-To: <4F8EFA24.8020909@hp.com> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 2012-04-18 at 10:30 -0700, Rick Jones wrote: > I was thinking more about the race if any between the ACK for the last > byte of the 64 KB skb and the transmit completion processing freeing it > in the driver. But that may be moot. > No race, its done with atomic operations. > > > > # perf stat -r 5 -d -d -o RES.before taskset 1 netperf -H 192.168.99.1 -l 20 > > I'm still learning about perf, and the manpage I have for it does not > discuss the -d option but is that doing system wide, or only in the > context of the netperf process? In fact I used -a option and forgot to copy it in the mail I sent perf stat -h usage: perf stat [] [] -e, --event event selector. use 'perf list' to list available events --filter event filter -i, --no-inherit child tasks do not inherit counters -p, --pid stat events on existing process id -t, --tid stat events on existing thread id -a, --all-cpus system-wide collection from all CPUs -g, --group put the counters into a counter group -c, --scale scale/normalize counters -v, --verbose be more verbose (show counter open errors, etc) -r, --repeat repeat command and print average + stddev (max: 100) -n, --null null run - dont start any counters -d, --detailed detailed run - start a lot of events -S, --sync call sync() before starting a run -B, --big-num print large numbers with thousands' separators -C, --cpu list of cpus to monitor in system-wide -A, --no-aggr disable CPU count aggregation -x, --field-separator print counts with custom separator -G, --cgroup monitor event in cgroup name only -o, --output output file name --append append to the output file --log-fd log output to fd, instead of stderr