Enhance db_bench to allow setting the number of levels in a database.
Enhance db_bench to allow setting the number of levels in a database.

Summary: Enhance db_bench to allow setting the number of levels in a database.

Test Plan: run db_bench and look at LOG

Reviewers: heyongqiang, MarkCallaghan

Reviewed By: MarkCallaghan

CC: MarkCallaghan

Differential Revision: https://reviews.facebook.net/D6027

virtdb/rocksdb,temicai/rocksdb,tsheasha/rocksdb,ryneli/rocksdb,anagav/rocksdb,fengshao0907/rocksdb,wenduo/rocksdb,fengshao0907/rocksdb,JoeWoo/rocksdb,geraldoandradee/rocksdb,JohnPJenkins/rocksdb,ylong/rocksdb,NickCis/rocksdb,vmx/rocksdb,JohnPJenkins/rocksdb,mbarbon/rocksdb,dkorolev/rocksdb,makelivedotnet/rocksdb,Andymic/rocksdb,siddhartharay007/rocksdb,IMCG/RcoksDB,JoeWoo/rocksdb,wskplho/rocksdb,temicai/rocksdb,zhangpng/rocksdb,JohnPJenkins/rocksdb,makelivedotnet/rocksdb,Andymic/rocksdb,IMCG/RcoksDB,amyvmiwei/rocksdb,fengshao0907/rocksdb,caijieming-baidu/rocksdb,zhangpng/rocksdb,vmx/rocksdb,Applied-Duality/rocksdb,msb-at-yahoo/rocksdb,virtdb/rocksdb,luckywhu/rocksdb,sorphi/rocksdb,luckywhu/rocksdb,fengshao0907/rocksdb,ryneli/rocksdb,Andymic/rocksdb,facebook/rocksdb,OverlordQ/rocksdb,norton/rocksdb,mbarbon/rocksdb,facebook/rocksdb,rDSN-Projects/rocksdb.replicated,jalexanderqed/rocksdb,alihalabyah/rocksdb,flabby/rocksdb,vmx/rocksdb,sorphi/rocksdb,wat-ze-hex/rocksdb,ylong/rocksdb,wlqGit/rocksdb,amyvmiwei/rocksdb,norton/rocksdb,sorphi/rocksdb,tschottdorf/rocksdb,JohnPJenkins/rocksdb,alihalabyah/rocksdb,wskplho/rocksdb,makelivedotnet/rocksdb,vashstorm/rocksdb,OverlordQ/rocksdb,tizzybec/rocksdb,skunkwerks/rocksdb,msb-at-yahoo/rocksdb,alihalabyah/rocksdb,jalexanderqed/rocksdb,Vaisman/rocksdb,JackLian/rocksdb,zhangpng/rocksdb,Applied-Duality/rocksdb,ryneli/rocksdb,tsheasha/rocksdb,Applied-Duality/rocksdb,geraldoandradee/rocksdb,facebook/rocksdb,virtdb/rocksdb,msb-at-yahoo/rocksdb,ylong/rocksdb,dkorolev/rocksdb,ylong/rocksdb,wat-ze-hex/rocksdb,wenduo/rocksdb,Andymic/rocksdb,mbarbon/rocksdb,rDSN-Projects/rocksdb.replicated,rDSN-Projects/rocksdb.replicated,Vaisman/rocksdb,wat-ze-hex/rocksdb,geraldoandradee/rocksdb,SunguckLee/RocksDB,dkorolev/rocksdb,skunkwerks/rocksdb,RyanTech/rocksdb,mbarbon/rocksdb,makelivedotnet/rocksdb,facebook/rocksdb,ylong/rocksdb,Applied-Duality/rocksdb,vmx/rocksdb,makelivedotnet/rocksdb,anagav/rocksdb,JohnPJenkins/rocksdb,alihalabyah/rocksdb,lgscofield/rocksdb,siddhartharay007/rocksdb,tizzybec/rocksdb,norton/rocksdb,siddhartharay007/rocksdb,dkorolev/rocksdb,wat-ze-hex/rocksdb,JoeWoo/rocksdb,jalexanderqed/rocksdb,jalexanderqed/rocksdb,flabby/rocksdb,vmx/rocksdb,msb-at-yahoo/rocksdb,JohnPJenkins/rocksdb,makelivedotnet/rocksdb,temicai/rocksdb,alihalabyah/rocksdb,vmx/rocksdb,virtdb/rocksdb,wlqGit/rocksdb,tschottdorf/rocksdb,Applied-Duality/rocksdb,mbarbon/rocksdb,hobinyoon/rocksdb,vashstorm/rocksdb,NickCis/rocksdb,flabby/rocksdb,kaschaeffer/rocksdb,SunguckLee/RocksDB,tizzybec/rocksdb,JackLian/rocksdb,tsheasha/rocksdb,kaschaeffer/rocksdb,anagav/rocksdb,alihalabyah/rocksdb,rDSN-Projects/rocksdb.replicated,RyanTech/rocksdb,OverlordQ/rocksdb,skunkwerks/rocksdb,NickCis/rocksdb,bbiao/rocksdb,JackLian/rocksdb,anagav/rocksdb,Vaisman/rocksdb,jalexanderqed/rocksdb,JackLian/rocksdb,siddhartharay007/rocksdb,SunguckLee/RocksDB,wat-ze-hex/rocksdb,fengshao0907/rocksdb,caijieming-baidu/rocksdb,JoeWoo/rocksdb,norton/rocksdb,skunkwerks/rocksdb,wlqGit/rocksdb,hobinyoon/rocksdb,amyvmiwei/rocksdb,lgscofield/rocksdb,wskplho/rocksdb,amyvmiwei/rocksdb,wlqGit/rocksdb,JohnPJenkins/rocksdb,geraldoandradee/rocksdb,amyvmiwei/rocksdb,biddyweb/rocksdb,tizzybec/rocksdb,luckywhu/rocksdb,luckywhu/rocksdb,temicai/rocksdb,bbiao/rocksdb,Vaisman/rocksdb,hobinyoon/rocksdb,wat-ze-hex/rocksdb,ryneli/rocksdb,bbiao/rocksdb,tizzybec/rocksdb,facebook/rocksdb,wenduo/rocksdb,biddyweb/rocksdb,sorphi/rocksdb,Andymic/rocksdb,amyvmiwei/rocksdb,sorphi/rocksdb,vashstorm/rocksdb,facebook/rocksdb,OverlordQ/rocksdb,SunguckLee/RocksDB,NickCis/rocksdb,wlqGit/rocksdb,vashstorm/rocksdb,kaschaeffer/rocksdb,rDSN-Projects/rocksdb.replicated,temicai/rocksdb,dkorolev/rocksdb,ryneli/rocksdb,Vaisman/rocksdb,sorphi/rocksdb,NickCis/rocksdb,zhangpng/rocksdb,siddhartharay007/rocksdb,kaschaeffer/rocksdb,temicai/rocksdb,sorphi/rocksdb,wenduo/rocksdb,lgscofield/rocksdb,msb-at-yahoo/rocksdb,dkorolev/rocksdb,anagav/rocksdb,lgscofield/rocksdb,Andymic/rocksdb,IMCG/RcoksDB,tsheasha/rocksdb,facebook/rocksdb,SunguckLee/RocksDB,vashstorm/rocksdb,hobinyoon/rocksdb,JoeWoo/rocksdb,RyanTech/rocksdb,tsheasha/rocksdb,zhangpng/rocksdb,Vaisman/rocksdb,biddyweb/rocksdb,flabby/rocksdb,JackLian/rocksdb,wenduo/rocksdb,dkorolev/rocksdb,biddyweb/rocksdb,siddhartharay007/rocksdb,JoeWoo/rocksdb,norton/rocksdb,ylong/rocksdb,bbiao/rocksdb,tschottdorf/rocksdb,geraldoandradee/rocksdb,tschottdorf/rocksdb,makelivedotnet/rocksdb,OverlordQ/rocksdb,zhangpng/rocksdb,caijieming-baidu/rocksdb,kaschaeffer/rocksdb,facebook/rocksdb,wat-ze-hex/rocksdb,JackLian/rocksdb,virtdb/rocksdb,caijieming-baidu/rocksdb,vmx/rocksdb,ylong/rocksdb,temicai/rocksdb,luckywhu/rocksdb,flabby/rocksdb,norton/rocksdb,RyanTech/rocksdb,fengshao0907/rocksdb,caijieming-baidu/rocksdb,rDSN-Projects/rocksdb.replicated,tsheasha/rocksdb,siddhartharay007/rocksdb,msb-at-yahoo/rocksdb,ryneli/rocksdb,jalexanderqed/rocksdb,alihalabyah/rocksdb,bbiao/rocksdb,amyvmiwei/rocksdb,IMCG/RcoksDB,luckywhu/rocksdb,skunkwerks/rocksdb,Andymic/rocksdb,mbarbon/rocksdb,wskplho/rocksdb,flabby/rocksdb,virtdb/rocksdb,IMCG/RcoksDB,ryneli/rocksdb,biddyweb/rocksdb,bbiao/rocksdb,luckywhu/rocksdb,wskplho/rocksdb,tizzybec/rocksdb,wskplho/rocksdb,rDSN-Projects/rocksdb.replicated,IMCG/RcoksDB,NickCis/rocksdb,norton/rocksdb,vashstorm/rocksdb,geraldoandradee/rocksdb,SunguckLee/RocksDB,wlqGit/rocksdb,SunguckLee/RocksDB,vashstorm/rocksdb,hobinyoon/rocksdb,OverlordQ/rocksdb,JackLian/rocksdb,anagav/rocksdb,JoeWoo/rocksdb,wenduo/rocksdb,hobinyoon/rocksdb,norton/rocksdb,RyanTech/rocksdb,RyanTech/rocksdb,anagav/rocksdb,Vaisman/rocksdb,wenduo/rocksdb,IMCG/RcoksDB,wskplho/rocksdb,skunkwerks/rocksdb,mbarbon/rocksdb,bbiao/rocksdb,kaschaeffer/rocksdb,Applied-Duality/rocksdb,tsheasha/rocksdb,wenduo/rocksdb,tschottdorf/rocksdb,lgscofield/rocksdb,lgscofield/rocksdb,biddyweb/rocksdb,caijieming-baidu/rocksdb,hobinyoon/rocksdb,flabby/rocksdb,skunkwerks/rocksdb,SunguckLee/RocksDB,tschottdorf/rocksdb,vmx/rocksdb,hobinyoon/rocksdb,NickCis/rocksdb,kaschaeffer/rocksdb,Andymic/rocksdb,fengshao0907/rocksdb,biddyweb/rocksdb,RyanTech/rocksdb,caijieming-baidu/rocksdb,tizzybec/rocksdb,tsheasha/rocksdb,Applied-Duality/rocksdb,virtdb/rocksdb,wlqGit/rocksdb,zhangpng/rocksdb,bbiao/rocksdb,OverlordQ/rocksdb,wat-ze-hex/rocksdb,lgscofield/rocksdb,jalexanderqed/rocksdb,geraldoandradee/rocksdb