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<== Date ==> <== Thread ==>

Subject: Re: EPICS Base Release-Candidate Double Feature!
From: Bruce Hill <[email protected]>
To: <[email protected]>
Date: Thu, 3 Nov 2016 15:35:45 -0700
The gateway source was updated Nov 2015 to support dynamic arrays,
but needed support in the PCAS which was just rolled out in 3.15.5
and 3.14.12.6 versions of base.

You will need to recompile the gateway using one of the above base
versions to get dynamic arrays to work across the gateway.

One caveat is that the client also needs to support dynamic arrays by
requesting zero elements via ca_array_get_callback and many common
clients such as edm, labca, and ezca don't do that yet.

Regards,
- Bruce

On 11/03/2016 02:47 PM, Andrew Johnson wrote:
Hi Keith,

I concur with the others, that particular change won't help gateways.

There was a change to the CAS that might help gateways a little though
iff they are being used to transport large arrays where the amount of
data included is smaller than the maximum array size (i.e. waveform
records that have NORD << NELM). I *think* this just needs a rebuild of
the gateway against the new Base, but hopefully Ralph Lange will confirm
that no code changes are needed in the gateway itself to take full
advantage of that update. Your CA clients should also be using
Base-3.14.12 or later, and be subscribing for dynamic-sized arrays.

- Andrew


On 11/03/2016 04:23 PM, Keith Thorne wrote:
Dear Andrew (and others)

	At LIGO, we appreciate the changes for faster loading of databases.

Question: do any of these changes (and the use of dbPvdTableSize shown below) relevant to EPICS gateways?
We have some very busy gateways (> 100,000 PVs) at present.

	Thanks
		Keith Thorne

On Nov 3, 2016, at 10:27 AM, Andrew Johnson <[email protected]> wrote:

Hi Murali,

On 11/02/2016 06:21 PM, Shankar, Murali wrote:
The 3.15 branch does contain a major performance improvement to the IOC
when loading large numbers of database records.
Awesome, I can load 100K PV's into a softIOC in a couple of seconds!
Thank you so much!
If you are loading large numbers of records also make sure that you are
setting the size of the IOC's hash-table before dbLoadDatabase() or
dbLoadRecords() in your startup script. The size argument must be a
power of 2 up to 64K:
    dbPvdTableSize(65536)
The default size is 512, although we should probably increase that
nowadays. More hash buckets means more efficient name searches both at
load-time and by the CA name resolution task.

- Andrew

--
Arguing for surveillance because you have nothing to hide is no
different than making the claim, "I don't care about freedom of
speech because I have nothing to say." -- Edward Snowdon
------
Keith Thorne <[email protected]>
CDS Software Engineer
LIGO Livingston Laboratory
Livingston, LA 70754
Phone: (225)686-3168 Fax: (225)686-7189



--
Bruce Hill
Member Technical Staff
SLAC National Accelerator Lab
2575 Sand Hill Road M/S 10
Menlo Park, CA  94025


References:
Re: EPICS Base Release-Candidate Double Feature! Shankar, Murali
Re: EPICS Base Release-Candidate Double Feature! Andrew Johnson
Re: EPICS Base Release-Candidate Double Feature! Keith Thorne
Re: EPICS Base Release-Candidate Double Feature! Andrew Johnson

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