Therefore we have tried jemalloc and it improved the performance of our cluster nearly twice as it was with glibc.
Installation was easy:
1. in the command line as root execute: yum install jemalloc
2. add to my.cnf following:
[mysqld_safe]
malloc-lib=/usr/lib64/libjemalloc.so.1
[mysqld_safe]
malloc-lib=/usr/lib64/libjemalloc.so.1
3. and now just restart mysql service with: service mysql restart
And here is the result of exchange of malloc library:
As you can see, the same hardware can process nearly twice SQLs. Not bad!