如何获取perf来解码hadoop java代码的符号

我在ubuntu 12.04上使用perf工具来分析hadoop 2.4.1 map/reduce作业的系统级性能:

perf record -ag -F 100 sleep 60

我的目标是确定哪些进程/例程正在使用cpu并确定优化候选者.

内核符号被正确解码,但java代码不是.Perf报告看起来像:

Samples: 39K of event 'cycles', Event count (approx.): 11326629675790000f9f0                                                                                                                                  â
+  10.64%           java  perf-9201.map               [.] 0x00007eff6c188127                                                                                                                                   
+  10.57%           java  perf-8988.map               [.] 0x00007f71ac7b9a29                                                                                                                                   
+   9.91%           java  perf-9077.map               [.] 0x00007fa9e92073e0                                                                                                                                   
+   9.77%           java  perf-9025.map               [.] 0x00007f849cdf41a9                                                                                                                                   
+   9.26%           java  perf-8747.map               [.] 0x00007f078c6bda82                                                                                                                                   
+   7.85%           java  perf-31343.map              [.] 0x00007f6671041cb4                                                                                                                                   
+   5.81%           java  perf-8835.map               [.] 0x00007f5df0d5afc4                                                                                                                                   
+   5.78%           java  liblzo2.so.2.0.0            [.] lzo1x_decompress                                                                                                                                     
+   2.61%           java  [kernel.kallsyms]           [k] copy_user_generic_string                                                                                                                             
+   1.58%           java  libc-2.15.so                [.] 0x000000000008ce40                                                                                                                                   
+   0.93%           java  perf-9677.map               [.] 0x00007f7c81012887                                                                                                                                   
+   0.86%        swapper  [kernel.kallsyms]           [k] intel_idle                                                                                                                                           
+   0.69%           java  libjvm.so                   [.] SpinPause                                                                                                                                            

所以问题是,我如何获得perf来解码java代码的符号？