Failed to find mmap entries in 'perf.data' for binaries

[huanglanzhiguan]

Hi,
I followed the guide to build llvm-propeller, it worked well with small binaries.
But encountered following issues when processing perf.data of a large binary:

E0825 16:17:57.031502 2792597 llvm_propeller_profile_writer.cc:1189] Failed to find mmap entries in 'perf.data' for XXX