IDS Forum

Re: NETTYPES and FASTPOLL = 1

Posted By: Art Kagel
Date: Friday, 23 October 2009, at 2:18 p.m.

In Response To: NETTYPES and FASTPOLL = 1 (Clifton Bean)

IBM recommends keeping the number of connections per poll thread under 350.
Although a single poll thread or NET VP can handle over 1000 connections,
apparently responsiveness is less than ideal with more than 350 connections
per NET VP. Personally, I like to configure for 200-250 per NET VP so that
unusual peak loads don't pull the total much over 350. However, there is no
good reason to configure way down to say 50 or 100 connections per NET VP.

As to the number of VPs on a system, the older limitation of a single VP per
processor core and the newer recommendations, that your management has read
about, refer to the CPU VPs specifically. The NET VPs rarely use sufficient
CPU resources that one need take them into consideration unless one require
a boat load of them. The rule of thumb that I developed several years ago
was one CPU VP per core per 450-500MHZ of processor power (use 750MHZ for
Intel processors and ignore hyper threads - they are NOT cores). This is
probably what your management has been reading. Over the years this has
held up very well, but again, doesn't address the NET VPs at all.

Honestly, I would not reduce the number of NET VPS below 8 (set with 350
connections each initially) and might agree with manaagement and recommend
increasing it to 10 ( set with 250 connections each initially) to keep
within my comfort zone of 200-250 connections per NET VP.

If your shared memory connection is used for more than just maintenance I
would configure the same number of shared memory listeners as CPU VPs and
configure the number of connections to be close to the actual peak shared
memory connection load (the 350 looks suspiciously like it was set to agree
with the TCP setting for convenience). If shared memory is only used for
maintenance, I like to configure two threads just in case the first CPU VP
(which runs the first listener thread) is busy or hung and I have to get
into the server NOW for some reason (yes that's happened to me).

Art

Art S. Kagel
Oninit (www.oninit.com)
IIUG Board of Directors (art@iiug.org)

Disclaimer: Please keep in mind that my own opinions are my own opinions and
do not reflect on my employer, Oninit, the IIUG, nor any other organization
with which I am associated either explicitly or implicitly. Neither do
those opinions reflect those of other individuals affiliated with any entity
with which I am affiliated nor those of the entities themselves.

On Fri, Oct 23, 2009 at 1:50 PM, Clifton Bean <clifton_bean@hotmail.com>wrote:

> IDS 11.5.FC5 AIX 5.3
>
> One (oldest) server: 10 CPU 1.6Ghz Power 5 Single Thread/CPU System
>
> One (newest) server: 16 CPU 3.8ghz Power 6 Multi-Core/CPU System (so, 32
> CPU
> thread allocation).
>
> NETTYPE ipcshm,1,350,CPU # Configure poll thread(s) for nettype
> NETTYPE soctcp,9,350,NET # Configure poll thread(s) for nettype
> FASTPOLL 1
>
> onstat –u | tail: 1774 active, 2304 total, 2231 maximum concurrent
>
> At least, initially, they will have approximately the same number of users
> when they complete their migration to the new server.
>
> I have recommended, for the oldest server, they reduce the number of NET
> threads from 9 to 7. That would be capable, using what I know, of easily
> handling 2450+ connections and, according to the Performance Guide,
> actually
> much, much more. [starting on page 3-12]
>
> To which management has replied:
> Interesting, I had read the opposite and had considered raising the number
> of
> polling threads. I had recently read that the limitation of one thread per
> CPU
> core was originally recommended based on much slower processors, but
> today’s
> processors could easily handle more than one thread, and that reducing the
> number of connections per polling thread would yield better performance.
> Could
> you do some more inquiries on this issue?
>
> So ... I would like to hear from others as to how to configure for the
> oldest
> server ... as well as the newest, as I have not worked on any dual core AIX
> servers before.
>
> Thanks in advance and have a great weekend.
> Clifton
>
> _________________________________________________________________
> Windows 7: Simplify your PC. Learn more.
>
>
> http://www.microsoft.com/Windows/windows-7/default.aspx?ocid=PID24727::T:WLMTAGL:ON:WL:en-US:WWL_WIN_evergreen1:102009
>
>
>
> *******************************************************************************
> Forum Note: Use "Reply" to post a response in the discussion forum.
>
>

--001517478d80b2f5d604769e3c79

Messages In This Thread

• NETTYPES and FASTPOLL = 1
  Clifton Bean -- Friday, 23 October 2009, at 1:50 p.m.
  • Re: NETTYPES and FASTPOLL = 1
    Art Kagel -- Friday, 23 October 2009, at 2:18 p.m.

IDS Forum is maintained by Administrator with WebBBS 5.12.