Hi Ru,
To turn off caching, add the option "-no_cache" in your gateway command.
Since you use "caput -c pvName", I guess "pvName" seems to be an asynchronous record. You can try this to find out how much time the command "caput -c" takes: time(caput -c pvName).
Another try: increase to the default timeout (1 second) to a bigger number (10 seconds), i.e. caput -c -w 10 pvName
HTH,
Yong
On 4/13/21, 5:52 PM, "Tech-talk on behalf of Johnson, Andrew N. via Tech-talk" <tech-talk-bounces at aps.anl.gov on behalf of tech-talk at aps.anl.gov> wrote:
What happens when you run a camonitor on the PV(s) at the same time as you do the put, does it show the full sequence that you're expecting?
ISTR there is a configuration setting for the CA gateway which can turn off cacheing, which may be what you want for one that you’re going caputs through; maybe someone else with more knowledge can comment on that.
- Andrew
> On Apr 13, 2021, at 4:33 PM, Ru Igarashi via Tech-talk <tech-talk at aps.anl.gov> wrote:
>
> Hello Hugo,
>
> Neither camonitor nor caget shows bad timestamps. Also, I forgot
> to mention that, when I do a caget right after a caput -c it returns
> with the correct value, and running a parallel camonitor exacerbates
> the problem. I plan on running more detailed tests with caget and
> camonitor, and with debugging turned on. But I would like to know
> if this is a familiar problem or that running CA Gateways on VMWare
> is a bad idea to begin with (I had big latency problems many years
> ago, so I went to a hardware solution at that time).
>
> ru
> ________________________________________
> From: Hugo Slepicka <hhslepicka at gmail.com>
> Sent: Tuesday, April 13, 2021 12:56
> To: Ru Igarashi
> Cc: tech-talk at aps.anl.gov
> Subject: External: Re: problems with running EPICS Gateway on virtual machines?
>
> Hi Ru,
>
> Could you check if doing a caget -a shows the timestamp as undefined?
>
> Another thing is: could you try to downgrade R2.0.6 and see if it works?
>
> Cheers,
> Hugo
>
> On Tue, Apr 13, 2021 at 10:44 AM Ru Igarashi via Tech-talk <tech-talk at aps.anl.gov<mailto:tech-talk at aps.anl.gov>> wrote:
>
> Hello,
> I have at least one problem with running EPICS CA Gateway 2.1.2
> on Scientific Linux/Redhat Enterprise Linux 7 with EPICS 3.14.12.4.
> For IOC's running EPICS 7 on CentOS 8 and clients on older OS and
> EPICS 3.14.12, the readback value for asynchronous 'caput' commands
> (caput -c) are often the old value, not new value. I have an older
> gateway running on old hardware, OS and EPICS which also does this
> but 100 times LESS frequently for the same type of IOC and client.
> The other difference between the two set-ups is that the new
> gateway is running on a virtual server (VMWare) and the old gateway
> is running on hardware.
>
>
> Further, when I see these errors, packet captures show the only
> differences in behaviour are that:
> - on the client side of the gateway, in the bad transaction, the
> "update" packet that follows the "write" arrives after the write
> is acknowledged whereas normal transactions have the
> acknowledgement packet arrive after the "update" packet.
> - on the server side of the gateway, in the bad transaction, the
> "update" packet carries a data payload of zeros in all bytes,
> whereas normal transactions have non-zero data payloads.
>
> It looks as if updates from the IOC are arriving late and
> the gateway is returning unusable data.
>
> I haven't ruled out server performance yet, but before I sink
> any more time into this, I'd like to ask, has anyone
> experienced problems running Gateways on virtual servers?
> Or could this be due to running the gateway on newer, higher
> performance machines, or due to mismatches in the way channel
> access is handled by EPICS 7 versus 3.14.12.4?
>
> ru
>
--
Complexity comes for free, simplicity you have to work for.
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