[
https://issues.apache.org/jira/browse/CASSANDRA-1902?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13016370#comment-13016370
]
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
