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Jonathan Ellis commented on CASSANDRA-4937: ------------------------------------------- bq. Practice shows that kernel is pretty efficient on reclaiming once used pages, when in need, and we still have writer that skips cache Shouldn't we just take out cache-skipping on [C]RAR entirely then? bq. I have actually experimented with preheating rows is we have compaction_preheat_key_cache enabled Why does this work better than the old mincore approach we tried? > CRAR improvements (object cache + CompressionMetadata chunk offset storage > moved off-heap). > ------------------------------------------------------------------------------------------- > > Key: CASSANDRA-4937 > URL: https://issues.apache.org/jira/browse/CASSANDRA-4937 > Project: Cassandra > Issue Type: Improvement > Reporter: Pavel Yaskevich > Assignee: Pavel Yaskevich > Fix For: 1.2.1 > > Attachments: CASSANDRA-4937.patch > > > After good amount of testing on one of the clusters it was found that in > order to improve read latency we need to minimize allocation rate that > compression involves, that minimizes GC (as well as heap usage) and > substantially decreases latency on read heavy workloads. > I have also discovered that RAR skip cache harms performance in situation > when reads are done in parallel with compaction working with relatively big > SSTable files (few GB and more). The attached patch removes possibility to > skip cache from compressed files (I can also add changes to RAR to remove > skip cache functionality as a separate patch). -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira