Dear all, Thanks for the good suggestions! I believe it is because the test client is single-threaded, so only server thread is serving it, so the rest of the cores are just sitting idle.
Thanks! -- Author of books for learning CXF, Axis2, Wicket, JSF (http://www.agileskills2.org) ________________________________ From: Peter Tillotson <slatem...@yahoo.co.uk> To: "user@cassandra.apache.org" <user@cassandra.apache.org>; Kent Tong <freemant2...@yahoo.com> Sent: Friday, December 16, 2011 1:45 AM Subject: Re: performance reaching plateau while the hardware is still idle May I suggest dstat, does cpu, memory, and io on one console dstat -vn 3 So possible causes * Not sufficient parrallelism in the client * Server has too few threads * You are not CPU bound, network or disk may be the bottleneck p ----- Original Message ----- From: Kent Tong <freemant2...@yahoo.com> To: "user@cassandra.apache.org" <user@cassandra.apache.org> Cc: Sent: Thursday, 15 December 2011, 10:58 Subject: performance reaching plateau while the hardware is still idle 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!
