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Date: Wed, 24 Jun 2015 21:54:05 +0000 (UTC)
From: "Joshua McKenzie (JIRA)" <jira@apache.org>
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Subject: [jira] [Created] (CASSANDRA-9648) Warn if power profile is not High
 Performance on Windows
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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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