Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Thu, 3 Nov 2016 16:47:02 -0500

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
> 
> 

-- 
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

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System