Experimental Physics and
Industrial Control System

Dirk Zimoch <[email protected]> · Mon, 22 Aug 2005 14:29:24 +0200

Hi Pete,
at SLS, we are using the gateway and have several problems.
Leicester, PJ (Pete) wrote:

No responses to my last email regarding large transfers through the
Gateway. I'd still like to get an idea of any potential problems in this
area so two questions:-
1) Is anyone doing large transfers through the gateway?
2) Has anyone tried large transfers and had problems?

Once, someone tried to read camera pictures through the gateway. The
result was that the gateway hung. It used up all cpu time but the
thoughput was zero. All clients disconencted.
On the gateway machine, EPICS_CA_MAX_ARRAY_BYTES was not set.
Setting EPICS_CA_MAX_ARRAY_BYTES big enough seemed to help, but you
can't know in advance how big "big enough" is. At least not on a generic
system like a gateway. Thus, the EPICS_CA_MAX_ARRAY_BYTES mechanism is
not really usable.
Since I already have so many other problems with the gateway, I disabled
access to the camera pictures. I did not try to run performance tests.
I am using the same versions of gateway and base as you do on the
gateway machine.
Best regards,
Dirk

Pete Leicester
Diamond Light Source Ltd.
Tel: 44 1235 778478

-----Original Message-----

From: Leicester, PJ (Pete) [mailto:[email protected]]
Sent: 01 August 2005 10:57

To: [email protected]

Subject: Gateway and EPICS_CA_MAX_ARRAY_BYTES

I have been trying to get a gateway running doing large transfers
(EPICS_CA_MAX_ARRAY_BYTES=3000000) but I am seeing performance problems.
I can get everything to work but only by restarting the gateway AFTER I
have booted the IOC and started the EDM client. In the working state the
Gateway clientEventRate/clientPostRate/serverEventRate/serverPostRate
are all at around 60Hz. If I then close the EDM client and restart it
the Gateway runs very slow, the event rate drops down to about 6 Hz
occasionally rising to 16Hz but it never recovers. If I reboot the
gateway without touching the IOC or EDM client I get back to the 60Hz
rate. At all times the event to post rates are much the same (i.e.
clientEventRate=clientPostRate and  serverEventRate=serverPostRate). I
only have 40 PV's in total, the gateway appears lightly loaded even when
running slow (loopRate=260,cpuFraction=0.06,load=0.05).
My test setup is as follows:
Client EDM screen running on linux/epics 3.14.6
Gateway version 2.0.0.0Beta18 running on linux/EPICS 3.14.7 cvs snapshot
taken on 14th April 05. IOC running Vxworks/EPICS 3.14.6 All have
EPICS_CA_MAX_ARRAY_BYTES=3000000 and the Client and Gateway both have
EPICS_CA_AUTO_ADDRESS_LIST=NO.
My questions are:-

1) Has anyone got large transfers to work reliably?
2) Should I be able to do large transfers with this setup?
3) Has anyone seen this problem before and what is going on when the

gateway is running slow?
Pete Leicester
Diamond Light Source Ltd.
Tel: 44 1235 778478

--
Dr. Dirk Zimoch
Swiss Light Source
Paul Scherrer Institut
Computing and Controls
phone +41 56 310 5182
fax   +41 56 310 4413

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System