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From "Joshua McKenzie (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CASSANDRA-9648) Warn if power profile is not High Performance on Windows
Date Wed, 24 Jun 2015 21:54:05 GMT
Joshua McKenzie created CASSANDRA-9648:
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             Summary: Warn if power profile is not High Performance on Windows
                 Key: CASSANDRA-9648
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-9648
             Project: Cassandra
          Issue Type: Improvement
            Reporter: Joshua McKenzie
            Assignee: Joshua McKenzie
            Priority: Minor
             Fix For: 2.2.x


Windows' power profiles have a pretty marked impact on application performance and the CPU
frequency throttling is fairly aggressive even in balanced mode. As we have a large number
of threads with varying work rather than a single busy thread-per-core, the scheduler on Windows
sees enough downtime to constantly struggle w/our user-space operations and the frequency
on the system will jump up and down even when fully saturated from a stress.

I've done some benchmarking of the "Balanced" vs. "High Performance" power profiles - [link
to performance numbers|https://docs.google.com/spreadsheets/d/1YS8VtdZAgyec-mcnSgtNhQH9LiHstOaiMtlppvEIIM8/edit#gid=0].
Note: reads are not saturating the box (or even impacting resources at all really) as the
CPU's on both stress and node are sitting around 4% usage. Still have something to figure
out there on 2.2.

We have a few ways we can approach this - for the 1st (warn), here's a branch with warning
during startup if non-High Performance power profile detected: [here|https://github.com/apache/cassandra/compare/trunk...josh-mckenzie:check_power_plan].

Alternatively we could get more aggressive and actually attempt a powercfg /s to the GUID
of the High Performance power profile or refuse to start Cassandra if we're not in the performance
profile. I also briefly pursued using Sigar to query this information however the documentation
for the library is no longer available (or at least I couldn't find it).



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