执行
logcat -g
查看当前logcat的buffer大小
例如：
root:/ $ logcat -g main: ring buffer is 16 MiB (2 MiB consumed), max entry is 5120 B, max payload is 4068 B system: ring buffer is 4 MiB (738 KiB consumed), max entry is 5120 B, max payload is 4068 B crash: ring buffer is 1 MiB (0 B consumed), max entry is 5120 B, max payload is 4068 B kernel: ring buffer is 16 MiB (313 KiB consumed), max entry is 5120 B, max payload is 4068 B