Cassandra and -XX:+UseLargePages

2011-01-16 Thread David Dabbs
Hello. Can anyone comment on the performance impact (positive or negative) of running Cassandra configured to use large pages under Linux? Yes, YMMV applies, but I thought I'd ask before enlisting sysadmin Fu, etc. Thanks! David

Re: Cassandra and -XX:+UseLargePages

2011-01-16 Thread Chris Goffinet
I've seen about a 13% improvement in practice. -Chris On Jan 16, 2011, at 4:01 PM, David Dabbs wrote: Hello. Can anyone comment on the performance impact (positive or negative) of running Cassandra configured to use large pages under Linux? Yes, YMMV applies, but I thought I'd ask before

Re: Cassandra and -XX:+UseLargePages

2011-01-16 Thread Aaron Morton
Chris, could you provide some more info on you experience? Were you using mmapped files? Using row or key caches? What were the memtabe thresholds? Using mlockall() ? There are a couple of issues listed in the first paragraphs here that at first glance may cause issues

RE: Cassandra and -XX:+UseLargePages

2011-01-16 Thread David Dabbs
-Original Message- From: Aaron Morton [mailto:aa...@thelastpickle.com] Sent: Sunday, January 16, 2011 7:07 PM To: user@cassandra.apache.org Subject: Re: Cassandra and -XX:+UseLargePages Chris, could you provide some more info on you experience? Were you using mmapped files? Using row

Re: RE: Cassandra and -XX:+UseLargePages

2011-01-16 Thread Aaron Morton
long enough.AOn 17 Jan, 2011,at 02:37 PM, David Dabbs dmda...@gmail.com wrote: -Original Message- From: Aaron Morton [mailto:aa...@thelastpickle.com] Sent: Sunday, January 16, 2011 7:07 PM To: user@cassandra.apache.org Subject: Re: Cassandra and -XX:+UseLargePages Chris, could you