[jira] [Commented] (CASSANDRA-3376) Track buffer cache hit rate with mincore
[ https://issues.apache.org/jira/browse/CASSANDRA-3376?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13801934#comment-13801934 ] Jonathan Ellis commented on CASSANDRA-3376: --- bq. we don't know how much of an sstable we'll need to read for a given slice ahead of time Thinking about it more, just checking the position where we start the slice would probably be Good Enough (certainly better than nothing). Track buffer cache hit rate with mincore Key: CASSANDRA-3376 URL: https://issues.apache.org/jira/browse/CASSANDRA-3376 Project: Cassandra Issue Type: New Feature Reporter: Jonathan Ellis Priority: Minor Labels: ponies We could use mincore on, say, 1% of reads to be able to report actual buffer cache hit rate. This would be useful when troubleshooting slow reads, e.g., are reads to CF X slow because it's hitting disk, or because there are a lot of tombstones in the row? -- This message was sent by Atlassian JIRA (v6.1#6144)
[jira] [Commented] (CASSANDRA-3376) Track buffer cache hit rate with mincore
[ https://issues.apache.org/jira/browse/CASSANDRA-3376?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13563114#comment-13563114 ] Jonathan Ellis commented on CASSANDRA-3376: --- Two thoughts: # The right way to do this now is probably to integrate with tracing -- if tracing is enabled, do the mincore check and trace the results; if not, don't bother # Actually implementing this would be a PITA because of our everything is an iterator read path -- we don't know how much of an sstable we'll need to read for a given slice ahead of time Track buffer cache hit rate with mincore Key: CASSANDRA-3376 URL: https://issues.apache.org/jira/browse/CASSANDRA-3376 Project: Cassandra Issue Type: New Feature Reporter: Jonathan Ellis Priority: Minor Labels: ponies We could use mincore on, say, 1% of reads to be able to report actual buffer cache hit rate. This would be useful when troubleshooting slow reads, e.g., are reads to CF X slow because it's hitting disk, or because there are a lot of tombstones in the row? -- 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
[jira] [Commented] (CASSANDRA-3376) Track buffer cache hit rate with mincore
[ https://issues.apache.org/jira/browse/CASSANDRA-3376?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13129849#comment-13129849 ] Jonathan Ellis commented on CASSANDRA-3376: --- Note that we already did a JNA mincore wrapper for CASSANDRA-1902 (which did not end up getting committed, but the patches are still there). Track buffer cache hit rate with mincore Key: CASSANDRA-3376 URL: https://issues.apache.org/jira/browse/CASSANDRA-3376 Project: Cassandra Issue Type: New Feature Reporter: Jonathan Ellis Priority: Minor Labels: ponies We could use mincore on, say, 1% of reads to be able to report actual buffer cache hit rate. This would be useful when troubleshooting slow reads, e.g., are reads to CF X slow because it's hitting disk, or because there are a lot of tombstones in the row? -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira
