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List:       openais
Subject:    [Openais] Fwd: hot nodes and timeoutes
From:       Steven Dake <steven.dake () gmail ! com>
Date:       2005-05-13 13:30:50
Message-ID: 8b9ac71b05051306305aadde8d () mail ! gmail ! com
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forgot to copy list..

---------- Forwarded message ----------
From: Steven Dake <steven.dake@gmail.com>
Date: May 13, 2005 6:30 AM
Subject: hot nodes and timeoutes
To: howlett@nortel.com


in response to your questions about performance at 30%...

Openais is constantly under network use because a token (or message)
is transported from each processor to the next in constant motion.
This provides the ordering, reliaibilithy, flow control, and
healthchecking of the protocol.

One mechanism we have done to reduce cpu utilization is to limit the
amoun of the token rotation during idle times (what you likely see as
the 30%).  This works to reduce cpu usage to less then .0.1% during
light traffic.  Unfortunately it introduced a latency in delay equal
to the time the token was held.

I am working on a patch at the moment that gets rid of the latency and
also provides the good performance characteristics of holding the
token.  The archives contain a good description of this approach if
you want to read it.

The key/value pairs in openais.conf used to control itmeouts are only
for the membershpi protocol.  By altering those timeout values, it is
possible to accelerate the rate at which faliure detection of a link
occurs.  We intend at some point to make this somewhat "automatic" as
part of the protocol rather then hard-coding them into the protocol.

When the protocol/openais is under heavy load, it will consume most of
the processor if nothing else is scheduled.  This is to be expected.

One mechanism to avoid high cpu utilization is to turn off
encryption/authentication which are responsible for 70-80% of the cpu
utiliziation.  Each byte transmitted takes about 100 clocks to add
encryption to and that adds up.

Regards
-steve.

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