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Pavel Yaskevich commented on CASSANDRA-6746: -------------------------------------------- [~enigmacurry] Thanks for the results, this looks promising although I one question for me remains why is there that deep for buffered-io patch, It might be related to the last compaction combining 4 sstables into one... Can you please do the following experiment - write the data, force a flush + major compaction, once all compactions complete run the buffered-io-tweaks patch to see if that deep in the middle of the run is actually caused by compaction replacing pre-heated file set with completely cold file? > Reads have a slow ramp up in speed > ---------------------------------- > > Key: CASSANDRA-6746 > URL: https://issues.apache.org/jira/browse/CASSANDRA-6746 > Project: Cassandra > Issue Type: Bug > Components: Core > Reporter: Ryan McGuire > Assignee: Benedict > Labels: performance > Fix For: 2.1 beta2 > > Attachments: 2.1_vs_2.0_read.png, 6746-buffered-io-tweaks.png, > 6746-patched.png, 6746.blockdev_setra.full.png, > 6746.blockdev_setra.zoomed.png, 6746.buffered_io_tweaks.logs.tar.gz, > 6746.txt, buffered-io-tweaks.patch, > cassandra-2.0-bdplab-trial-fincore.tar.bz2, > cassandra-2.1-bdplab-trial-fincore.tar.bz2 > > > On a physical four node cluister I am doing a big write and then a big read. > The read takes a long time to ramp up to respectable speeds. > !2.1_vs_2.0_read.png! > [See data > here|http://ryanmcguire.info/ds/graph/graph.html?stats=stats.2.1_vs_2.0_vs_1.2.retry1.json&metric=interval_op_rate&operation=stress-read&smoothing=1] -- This message was sent by Atlassian JIRA (v6.2#6252)