[rds-devel] RDS IB transport software flow control?
zach.brown at oracle.com
Tue Nov 6 08:48:34 PST 2007
> RDS can be quite memory
> hungry, if you let it run unchecked; and once you do run into a congestion
> scenario, things will actually get quite slow, as congestion updates
> involve sending the entire 8K congestion map down all RCs.
The input I was given is that it's acceptable to require that
deployments very carefully tune the amount of data they'll have in the
network. It's like tuning the database's SGA size. If you get it wrong
the system will be very unhappy.
That's why congestion updates are trivial but expensive. If they're
happening its a fundamental mistuning of a closed system that should be
lighting up pagers, not some natural side-effect of load like it is for
TCP over the big-bad-internet.
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