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dbEvent tweak Queue size
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@mdavidsaver
mdavidsaver committed Jun 26, 2019
1 parent 5b09bb6 commit c8e5dec
Showing 1 changed file with 7 additions and 1 deletion.
8 changes: 7 additions & 1 deletion modules/database/src/ioc/db/dbEvent.c
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Expand Up @@ -49,7 +49,13 @@
#include "link.h"
#include "special.h"

#define EVENTSPERQUE 32
/* Queue size based on Ethernet MTU of 1500 bytes.
* Assume <=66 bytes of ethernet+IP+TCP overhead
* and 40 byte CA messages (DBF_TIME_DOUBLE).
*
* (1500-66)/40 -> 35
*/
#define EVENTSPERQUE 36
#define EVENTENTRIES 4 /* the number of que entries for each event */
#define EVENTQUESIZE (EVENTENTRIES * EVENTSPERQUE)
#define EVENTQEMPTY ((struct evSubscrip *)NULL)
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3 comments on commit c8e5dec

@mdavidsaver
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@anjohnson @ralphlange This change didn't reach my threshold for a merge request, but I do want to point it out. It is based on some testing I did looking at how fast scalar DBR_TIME_DOUBLE monitor updates could be transfered via. CA. Packet captures showed that even at high rate Ethernet frames were only 1306 bytes long. This change can squeeze a few more bytes into each frame.

I don't think it will have any ill-effects for other DBR_ types.

@ralphlange
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Yea. Agree that this should be fine.

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Thanks for the explanation, no objections from me.

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