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From "Ryan McGuire (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (CASSANDRA-4860) Estimated Row Cache Entry size incorrect (always 24?)
Date Tue, 16 Apr 2013 16:51:17 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-4860?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13632970#comment-13632970
] 

Ryan McGuire edited comment on CASSANDRA-4860 at 4/16/13 4:50 PM:
------------------------------------------------------------------

I increased my key_cache_size_in_mb and did in fact get better results:

{code}
Averages from the middle 80% of values:
interval_op_rate          : 27848
interval_key_rate         : 27848
latency median            : 0.7
latency 95th percentile   : 1.4
latency 99.9th percentile : 22.4
Total operation time      : 00:01:20
{code}

The old measure() way with 300M key cache:
{code}
Running stress : -n 2000000 -o read -i 1
output is hidden while collecting stats...
Averages from the middle 80% of values:
interval_op_rate          : 27877
interval_key_rate         : 27877
latency median            : 0.7
latency 95th percentile   : 1.5
latency 99.9th percentile : 23.4
Total operation time      : 00:01:20
{code}

This is roughly equal to the original messure() method in read performance, I'm happy with
it!
                
      was (Author: enigmacurry):
    I increased my key_cache_size_in_mb and did in fact get better results:

{code}
Averages from the middle 80% of values:
interval_op_rate          : 27848
interval_key_rate         : 27848
latency median            : 0.7
latency 95th percentile   : 1.4
latency 99.9th percentile : 22.4
Total operation time      : 00:01:20
{code}

The old measure way with 300M key cache:
{code}
Running stress : -n 2000000 -o read -i 1
output is hidden while collecting stats...
Averages from the middle 80% of values:
interval_op_rate          : 27877
interval_key_rate         : 27877
latency median            : 0.7
latency 95th percentile   : 1.5
latency 99.9th percentile : 23.4
Total operation time      : 00:01:20
{code}

This is roughly equal to the original messure() method in read performance, I'm happy with
it!
                  
> Estimated Row Cache Entry size incorrect (always 24?)
> -----------------------------------------------------
>
>                 Key: CASSANDRA-4860
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4860
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 1.1.0, 1.2.3, 2.0
>            Reporter: Chris Burroughs
>            Assignee: Vijay
>             Fix For: 1.2.0 beta 3
>
>         Attachments: 0001-4860-v2.patch, 0001-4860-v3.patch, 0001-CASSANDRA-4860-for-11.patch,
0001-CASSANDRA-4860.patch, 4860-perf-test.zip, trunk-4860-revert.patch
>
>
> After running for several hours the RowCacheSize was suspicious low (ie 70 something
MB)  I used  CASSANDRA-4859 to measure the size and number of entries on a node:
> In [3]: 1560504./65021
> Out[3]: 24.0
> In [4]: 2149464./89561
> Out[4]: 24.0
> In [6]: 7216096./300785
> Out[6]: 23.990877204647838
> That's RowCacheSize/RowCacheNumEntires  .  Just to prove I don't have crazy small rows
the mean size of the row *keys* in the saved cache is 67 and Compacted row mean size: 355.
 No jamm errors in the log
> Config notes:
> row_cache_provider: ConcurrentLinkedHashCacheProvider
> row_cache_size_in_mb: 2048
> Version info:
>  * C*: 1.1.6
>  * centos 2.6.32-220.13.1.el6.x86_64
>  * java 6u31 Java HotSpot(TM) 64-Bit Server VM (build 20.6-b01, mixed mode)

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