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Jeff Jirsa commented on CASSANDRA-13896: ---------------------------------------- [~PrinceNana] - do you have an opinion on [~burmanm]'s patch? cc [~aweisberg] for visibility. > Improving Cassandra write performance > --------------------------------------- > > Key: CASSANDRA-13896 > URL: https://issues.apache.org/jira/browse/CASSANDRA-13896 > Project: Cassandra > Issue Type: Improvement > Components: Local Write-Read Paths > Environment: Skylake server with 2 sockets, 192GB RAM, 3xPCIe SSDs > OS: Centos 7.3 > Java: Oracle JDK1.8.0_121 > Reporter: Prince Nana Owusu Boateng > Priority: Major > Labels: Performance > Fix For: 4.x > > Attachments: Screen Shot 2017-09-22 at 11.22.43 AM.png, Screen Shot > 2017-09-22 at 3.31.09 PM.png > > > During our Cassandra performance testing, we see high percentage of the CPU > spent in *org.apache.cassandra.utils.memory.SlabAllocator.allocate(int, > OpOrder Group) * method. Appears to be high contention of the > *<nextFreeOffset>* atomic Integer in write workloads. This structure is > used by the threads for keeping track of the region bytebuffer allocation. > When the contention appears, adding more clients, modifications of write > specific parameters does not change write throughput performance. Attached > are the details of Java Flight Recorder (JFR), showing hot functions and also > performance results. When we see this contention, we still have plenty of > CPU and throughput left ( *<20%* Total average CPU utilization and *<11%* > of the storage write total throughput). This occurs on Cassandra 3.10.0-src > version using the Cassandra-Stress. > Proposal: > We will like to introduce a solution which eliminates the atomic operations > on the *<nextFreeOffset>* atomic Integer. This implementation will allow > concurrent allocation of bytebuffers without an atomic compareAndSet and > incrementAndGet operations. The solution is expected to increase overall > write performance while improving CPU utilization. -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@cassandra.apache.org For additional commands, e-mail: commits-h...@cassandra.apache.org