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Pavel Yaskevich commented on CASSANDRA-1902: -------------------------------------------- My results comparing OLD and NEW (with migration enabled) (rackspace server with 2GB ram the same as in prev. comments): script (stress.java) I run (while last compaction goes I run "-n 100000 -o read" in the separate terminal) {noformat} ./bin/stress -n 100000 -S 1024 -c 10 sleep 50 ./bin/stress -n 100000 -S 1024 -c 10 -o read ./bin/stress -n 100000 -S 1024 -c 10 -o read ./bin/stress -n 100000 -S 1024 -c 10 ../../bin/nodetool -h localhost flush Keyspace1 Standard1 echo "start reading" ../../bin/nodetool -h localhost compact Keyspace1 Standard1 {noformat} Results (OLD | NEW): {noformat} 191 | 182 (write) 22 | 22 (read) 16 | 16 (read) 184 | 182 (write) 171 | 176 (reads during compaction) 55 | 39 (read after compaction was finished) {noformat} I don't post results for new code with migration turned off because it shows the same results as OLD code except last read after compaction shows improvement - 44 vs 55. > Migrate cached pages during compaction > --------------------------------------- > > Key: CASSANDRA-1902 > URL: https://issues.apache.org/jira/browse/CASSANDRA-1902 > Project: Cassandra > Issue Type: Improvement > Components: Core > Affects Versions: 0.7.1 > Reporter: T Jake Luciani > Assignee: Pavel Yaskevich > Fix For: 0.7.5, 0.8 > > Attachments: > 0001-CASSANDRA-1902-cache-migration-impl-with-config-option.txt, > 1902-BufferedSegmentedFile-logandsleep.txt, 1902-formatted.txt, > 1902-per-column-migration-rebase2.txt, 1902-per-column-migration.txt, > CASSANDRA-1902-v3.patch, CASSANDRA-1902-v4.patch, CASSANDRA-1902-v5.patch, > CASSANDRA-1902-v6.patch, CASSANDRA-1902-v7.patch > > Original Estimate: 32h > Time Spent: 56h > Remaining Estimate: 0h > > Post CASSANDRA-1470 there is an opportunity to migrate cached pages from a > pre-compacted CF during the compaction process. This is now important since > CASSANDRA-1470 caches effectively nothing. > For example an active CF being compacted hurts reads since nothing is cached > in the new SSTable. > The purpose of this ticket then is to make sure SOME data is cached from > active CFs. This can be done my monitoring which Old SSTables are in the page > cache and caching active rows in the New SStable. > A simpler yet similar approach is described here: > http://insights.oetiker.ch/linux/fadvise/ -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira