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<== Date ==> | <== Thread ==> |
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Subject: | RE: Waveform record I/O interrupt. asyn |
From: | "Hill, Jeff" <[email protected]> |
To: | Ralph Lange <[email protected]>, EPICS Tech Talk <[email protected]> |
Date: | Tue, 25 Feb 2014 18:58:34 +0000 |
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The - already implemented - server-side CA plugins/filters in 3.15 can
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also achieve this behavior. An issue with this approach is that such plugins are subscription specific (i.e. client
and event queue specific), and therefore the same payload, including site specific parameters together with the array data, are not typically shared, that is reference-counted, on multiple queues for multiple CA clients over multiple different filter types
and expressions. Also, issues with reordering of events, subscription-xxx versus subscription-yyy, remain in R3.15 substantially unchanged, inherited from the legacy implementation which I authored. I also have some personal concerns
about disruption of timing system synchronized record processing by application installed high-priority-side-of-the-event-queue per-subscription-event-filtering; I am concerned that this does not scale as the load due to a variable number of subscriptions
introduced at run-time increases. Yes, the users might only install very low overhead filters to run at record processing priority, but I worry that such an architecture is opening up broad avenues for EPICS to become a less than robust system unless users
are very diligent. I am concerned that a real time activity that is proven to be working might be more likely to be unexpectedly disrupted in the future by an increasing magnitude of the client load. Finally, my personal perspective is that my approach, initiated
first and described in previous talks, is a more generalized architectural upgrade allowing site-specific parasitic parameters to pass transparently through EPICS from the device support data-originator to the data-consumer. Jeff From:
[email protected] [mailto:[email protected]] On Behalf Of
Ralph Lange On Sat Feb 22 2014 02:25:30 GMT+0100 (CET), Hill, Jeff
<[email protected]> wrote:
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