Experimental Physics and Industrial Control System
Matt,
> What is the expected behaviour of the CA server when available free memory
> (or the largest free block) gets low on an IOC? We have occasionally had
> situations where free memory gets to ~200 KB and the largest free block gets
> to ~50-80 KB. The next time a client attempts a connection we see the warning
> "Unable to allocate additional dynamic memory". I believe that the CA server
> is working as it should. Is this true?
The CA server attempts to prevent additional memory consumption
after the max free block value drops below 100k. It is difficult
under vxWorks to examine the max free block value efficiently
because the routine provided examines every free block. They (WRS)
should probably keep track of the max free block on the fly.
Because of these inefficiencies we poll the max free block value
every few seconds. This opens up the possibility of a fast client
using up the memory pad before the next time that the max free block
value is polled.
Under EPICS 3.12.1. when the max free block
drops below 100k the server will not allow any additional channels to
be created even if the server's free list is populated. This can result
in failure to communicate with an overloaded IOC even if some of
the clients attached to the IOC are stopped in an attempted to
reduce the load. I have made changes for 3.12.2 to allow new channels
if the max free block is above 100k _or_ if the appropriate free
lists are populated.
Jeff
______________________________________________________________________
Jeffrey O. Hill Internet [email protected]
LANL MS H820 Voice 505 665 1831
Los Alamos, NM 87545 USA FAX 505 665 5107
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