I'm running rhel 5.7 and found there's no man page for "perf". How can I install one, any package name or yum name contains "perf"?
I think perf is available from RHEL 6 on. Did you mean to say you were using RHEL 6.7 ? Your RHEL 5.7 is a critically old and probably has several critical security issues and vulnerabilities. Also all production support on RHEL 5 systems ceases 31/03/2017 which is pretty close ! See https://access.redhat.com/support/policy/updates/errata for more detail
If you are actually using RHEL 6.7 it should be easy to install perf with yum:
yum install perf
provided you have set up the repositories or have the install media handy.