On Thu, Sep 25, 2014 at 7:57 AM, Jesper Dangaard Brouer
[off-list ref] wrote:

On Thu, 25 Sep 2014 07:40:33 -0700
Tom Herbert [off-list ref] wrote:

quoted

A few test results in patch 0 are good. I like to have results for
with and without patch. These should two things: 1) Any regressions
caused by the patch 2) Performance gains (in that order of importance
:-) ). There doesn't need to be a lot here, just something reasonably
representative, simple, and should be easily reproducible. My
expectation in bulk dequeue is that we should see no obvious
regression and hopefully an improvement in CPU utilization-- are you
able to verify this?

We are saving 3% CPU, as I described in my post with subject:
"qdisc/UDP_STREAM: measuring effect of qdisc bulk dequeue":
 http://thread.gmane.org/gmane.linux.network/331152/focus=331154

Using UDP_STREAM on 1Gbit/s driver igb, I can show that the
_raw_spin_lock calls are reduced with approx 3%, when enabling
bulking of just 2 packets.

That's great. In commit log, would be good to have results with
TCP_STREAM also and please report aggregate CPU utilization changes
(like from mpstat).

Thanks,
Tom

This test can only demonstrates a CPU usage reduction, as the
throughput is already at maximum link (bandwidth) capacity.

Notice netperf option "-m 1472" which makes sure we are not sending
UDP IP-fragments::

 netperf -H 192.168.111.2 -t UDP_STREAM -l 120 -- -m 1472

Results from perf diff::

 # Command: perf diff
 # Event 'cycles'
 # Baseline  Delta    Symbol
 # no-bulk   bulk(1)
 # ........  .......  .........................................
 #
     7.05%   -3.03%  [k] _raw_spin_lock
     6.34%   +0.23%  [k] copy_user_enhanced_fast_string
     6.30%   +0.26%  [k] fib_table_lookup
     3.03%   +0.01%  [k] __slab_free
     3.00%   +0.08%  [k] intel_idle
     2.49%   +0.05%  [k] sock_alloc_send_pskb
     2.31%   +0.30%  netperf  [.] send_omni_inner
     2.12%   +0.12%  netperf  [.] send_data
     2.11%   +0.10%  [k] udp_sendmsg
     1.96%   +0.02%  [k] __ip_append_data
     1.48%   -0.01%  [k] __alloc_skb
     1.46%   +0.07%  [k] __mkroute_output
     1.34%   +0.05%  [k] __ip_select_ident
     1.29%   +0.03%  [k] check_leaf
     1.27%   +0.09%  [k] __skb_get_hash

A nitpick is that, this testing were done on V2 of the patchset.

--
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Sr. Network Kernel Developer at Red Hat
  Author of http://www.iptv-analyzer.org
  LinkedIn: http://www.linkedin.com/in/brouer