RELENG_10 performance regression (was Re: 35-40% performance drop releng9 vs releng10 openvpn

[Mike Tancsa]

OK, just to refocus,

I had been tracking down what I thought was a regression between RELENG9 
and RELENG10, but looks more like an issue that cropped up somewhere 
between the beginning of March and now.  For RELENG9, I was actually 
using a kernel from sources back on Jan 29th by accident.  If I bring 
RELENG9 upto today, I get a similar performance loss.

Again, I am testing a simple VPN router setup

server1 --- apu --- server2

where server1 connections to the apu via an OpenVPN tunnel and server1 
sends packets via netblast across the tunnel to server2.

  I get the following throughput using netblast through the tunnel on 10

Using
# netblast 1.1.2.2 500 1200 15 (server1 to server2) on 10.x

Kernel    Mb/s
   rev
r277684  76.7563
r279978  59.3233

All good at r278533, r278534, r279467

But at r279978 its quite a bit slower.  So somewhere between r279467 and 
r279978.  I will keep trying to narrow it down...


	---Mike





On 3/19/2015 8:26 PM, Mike Tancsa wrote:
> On 3/18/2015 5:14 PM, John-Mark Gurney wrote:
>> # dtrace -x stackframes=100 -n 'profile-997 /arg0/ { @[stack()] =
>> count(); } tick-60s { exit(0); }' -o out.kern_stacks
>>
>> Also, another thing you can do is to compare the two using differential
>> flame graphs:
>> http://www.brendangregg.com/blog/2014-11-09/differential-flame-graphs.html
>>
>>
>> Which will highlight where the performances differ...
>
> OK, some more data points.  It seems a performance regression happened
> in RELENG_10 somewhere between r277684 (late January 2015) and now.
> Using r277684 on RELENG_10, I can get about 75Mb/s of throughput on
> OpenVPN. Still not as good as the 83-85Mb on RELENG_9, but much better
> than the 61Mb using RELENG_10 from the start of this week,
>
> For the differential graph, see
>
> http://tancsa.com/diffgraph.svg
>
> and
>
> http://tancsa.com/10-r277684.svg
> http://tancsa.com/10-r277684-kern.svg
>
>      ---Mike
>
>
>
>


-- 
-------------------
Mike Tancsa, tel +1 519 651 3400
Sentex Communications, mike at sentex.net
Providing Internet services since 1994 www.sentex.net
Cambridge, Ontario Canada   http://www.tancsa.com/