CPU usage is limited to 50%

Ammar

I have a cluster of 1+16 machines. The master machine has 2 cores, while the 16 slave machines have 4 cores. 

 

I run some complex queries that take minutes to finish. Unfortunately, I noticed that all salve machines use at most 50% of their CPU power. 

 

Does any one know the reason?

 

Thanks,

-Khaled

eli_revach

Hi ,

At a  basic ,  in Vertica there is no such notation  of Master servers , all servers  are the same , as such all server  HW specs should be the same .

Regarding your specific use case , I advise you  to  profile your query   , this will let you know where the query is spend most of the time .

 

This is good reference to start with http://www.vertica-forums.com/viewtopic.php?t=1334

 

Hope you find it usefully  

 

Thanks

Ammar

Thank you for your reply.

 

I will use one HW spec for all machines. My workload is graph analytics. I am following this paper : http://arxiv.org/abs/1412.5263

 

Thanks,

-Khaled

Ammar

Alright,

 

I used a cluster of the same machine and the performance was still limited to maximum 80%. However, since I was joining multiple tables, the network communication was very high and the preformance was reduced to less than 40%.

 

Is there any best practices / configuration parameters to enhance Vertica performance ?

 

Thanks,

-Khaled

 

SruthiA

Hi,

 

    Performance issues are very difficult to isolate. Performance of the cluster can decrease due to various reasons. Please run vcpuperf to validate CPU performance of your cluster

 

http://my.vertica.com/docs/7.2.x/HTML/index.htm#Authoring/InstallationGuide/scripts/vcpuperf.htm?Highlight=cpu performance

 

Please go through the following link and make sure that all configuration parameters are set to recommended values

 

http://my.vertica.com/docs/7.2.x/HTML/index.htm#Authoring/InstallationGuide/BeforeYouInstall/OsConfigTaskOverview.htm%3FTocPath%3DInstalling%2520Vertica%7CBefore%2520You%2520Install%2520Vertica%7COperating%2520System%2520Configuration%2520Task%2520Overview%7C_____0

 

If cluster is performing slow when you are running specific query. check query plan. for example queries using hash join perform slower than that use merge join.  Please go through the below URL which provides useful information on troubleshooting your slow performing database

 

 

http://my.vertica.com/docs/7.2.x/HTML/index.htm#Authoring/OEMCookbook/Maintaining/TroubleshootingPerformance.htm?Highlight=cpu performance

 

Thank you,

 Sruthi