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https://issues.apache.org/jira/browse/CASSANDRA-10326?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14877261#comment-14877261
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Benedict edited comment on CASSANDRA-10326 at 9/19/15 6:57 PM:
---------------------------------------------------------------
So, [this
comparison|http://cstar.datastax.com/graph?stats=518e5484-5ee3-11e5-b421-42010af0688f&metric=99.9th_latency&operation=1_user&smoothing=1&show_aggregates=true&xmin=0&xmax=865.37&ymin=0&ymax=158.51]
is especially interesting. With CASSANDRA-10322 now in, reverting GC settings
to those we have for 2.2 brings things much closer.
* Latency drops across the board - we're now better than 2.2 for all latency
metrics
* Throughput is still marginally worse for mixed, and latest queries
* Performance improves 40% for a point query, and 3.0 is now 10% _faster_ than
2.2 for these, instead of 20% slower
As such, I would recommend that - until we can assess the GC behavioural
changes further, we revert CASSANDRA-7486
It's also worth noting that this synchronisation of GC config demonstrates a
clear uptick in garbage in 3.0, that may explain a majority of the remaining
performance delta. So it may be worth profiling allocations to see if there are
any areas where quick wins are possible.
was (Author: benedict):
So, [this
comparison|http://cstar.datastax.com/graph?stats=518e5484-5ee3-11e5-b421-42010af0688f&metric=99.9th_latency&operation=1_user&smoothing=1&show_aggregates=true&xmin=0&xmax=865.37&ymin=0&ymax=158.51]
is especially interesting. With CASSANDRA-10322 now in, reverting GC settings
to those we have for 2.2 brings things much closer.
* Latency drops across the board - we're now better than 2.2 for all latency
metrics
* Throughput is still marginally worse for mixed, and latest queries
* Performance improves 40% for a point query, and 3.0 is now 10% _faster_ than
2.2 for these, instead of 20% slower
As such, I would recommend that - until we can assess the GC behavioural
changes further, we revert CASSANDRA-7486
> Performance is worse in 3.0
> ---------------------------
>
> Key: CASSANDRA-10326
> URL: https://issues.apache.org/jira/browse/CASSANDRA-10326
> Project: Cassandra
> Issue Type: Bug
> Reporter: Benedict
> Priority: Critical
> Fix For: 3.0.x
>
>
> Performance is generally turning out to be worse after 8099, despite a number
> of unrelated performance enhancements being delivered. This isn't entirely
> unexpected, given a great deal of time was spent optimising the old code,
> however things appear worse than we had hoped.
> My expectation was that workloads making extensive use of CQL constructs
> would be faster post-8099, however the latest tests performed with very large
> CQL rows, including use of collections, still exhibit performance below that
> of 2.1 and 2.2.
> Eventually, as the dataset size grows large enough and the locality of access
> is just right, the reduction in size of our dataset will yield a window
> during which some users will perform better due simply to improved page cache
> hit rates. We seem to see this in some of the tests. However we should be at
> least as fast (and really faster) off the bat.
> The following are some large partition benchmark results, with as many as 40K
> rows per partition, running LCS. There are a number of parameters we can
> modify to see how behaviour changes and under what scenarios we might still
> be faster, but the picture painted isn't brilliant, and is consistent, so we
> should really try and figure out what's up before GA.
> [trades-with-flags (collections),
> blade11b|http://cstar.datastax.com/graph?stats=f0a17292-5a13-11e5-847a-42010af0688f&metric=op_rate&operation=1_user&smoothing=1&show_aggregates=true&xmin=0&xmax=4387.02&ymin=0&ymax=122951.4]
> [trades-with-flags (collections),
> blade11|http://cstar.datastax.com/graph?stats=e25aaaa0-5a13-11e5-ae0d-42010af0688f&metric=op_rate&operation=1_user&smoothing=1&show_aggregates=true&xmin=0&xmax=4424.75&ymin=0&ymax=130158.6]
> [trades (no collections),
> blade11|http://cstar.datastax.com/graph?stats=9b7da48e-570c-11e5-90fe-42010af0688f&metric=op_rate&operation=1_user&smoothing=1&show_aggregates=true&xmin=0&xmax=2682.46&ymin=0&ymax=142547.9]
> [~slebresne]: will you have time to look into this before GA?
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