Default concurrency values are improperly proportioned
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Key: CASSANDRA-1972
URL: https://issues.apache.org/jira/browse/CASSANDRA-1972
Project: Cassandra
Issue Type: Bug
Reporter: Stu Hood
Assignee: Stu Hood
Priority: Minor
Fix For: 0.7.1
The "default"/"suggested" {{concurrent_reads}} value is much too low. It
assumes that CPU will be the bottleneck, rather than IO, and for most
deployments, this will not be the case. Additionally it is better to be queued
for IO in the kernel or on your device than in user space, because the former
work to optimize queue order.
Additionally, reads are much cheaper than writes in terms of CPU time (since
writes can experience contention due to retries), so while
{{concurrent_writes}} should probably factor in the number of cores on the
machine, {{concurrent_reads}} should probably be calculated purely by number of
spindles.
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