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Date: Thu, 15 Dec 2011 15:13:30 +0400
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Subject: Re: performance reaching plateau while the hardware is still idle
From: ruslan usifov <ruslan.usifov@gmail.com>
To: user@cassandra.apache.org, Kent Tong <freemant2000@yahoo.com>
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Use parallel test:-)))

2011/12/15 Kent Tong <freemant2000@yahoo.com>

> Hi,
>
> I am running a performance test for Cassandra 1.0.5. It can perform about
> 1500 business operation (one read+one write to the same row) per second.
> However, the CPU is still 85% idle (as shown by vmstat) and the IO
> utilization is less than a few percent (as shown by iostat). "nodetool
> tpstats" shows basically no active and pending threads. I can run several
> such test clients concurrently, achieving the same operations per second
> without increasing the hardware utilization. So, why the performance has
> reached a plateau while there is still idle hardware resources?
>
>
> Thanks in advance for any idea!
>

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Use parallel test:-)))<br><br><div class=3D"gmail_quote">2011/12/15 Kent To=
ng <span dir=3D"ltr">&lt;<a href=3D"mailto:freemant2000@yahoo.com">freemant=
2000@yahoo.com</a>&gt;</span><br><blockquote class=3D"gmail_quote" style=3D=
"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hi,<br>
<br>
I am running a performance test for Cassandra 1.0.5. It can perform about 1=
500 business operation (one read+one write to the same row) per second. How=
ever, the CPU is still 85% idle (as shown by vmstat) and the IO utilization=
 is less than a few percent (as shown by iostat). &quot;nodetool tpstats&qu=
ot; shows basically no active and pending threads. I can run several such t=
est clients concurrently, achieving the same operations per second without =
increasing the hardware utilization. So, why the performance has reached a =
plateau while there is still idle hardware resources?<br>

<br>
<br>
Thanks in advance for any idea!<br>
</blockquote></div><br>

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