Failed to understand the argument when executing single benchmark test

Testing with the whole suite takes a long time, and it's unnecessary if there's only one benchmark's result of interest. In my case it's Prot Fault which belongs to File&VM system latencies group.
After successfully building the whole lmbench suite, I tried to run the single benchmark case by going to the /bin/$ARCH-pc-linux-gnu directory under the lmbench directory and runing command ./lat_sig prot . However, it prompts the following info, seems like my usage was somewhat wrong.

```
root@jys-optiplex7060:/opt/lmbench-3.0-a9-1/bin/x86_64-pc-linux-gnu# ./lat_sig prot
Usage: ./lat_sig [-P ] [-W ] [-N ] install|catch|prot [file]
```

And then I ran as following but it still look wrong.
```
root@jys-optiplex7060:/opt/lmbench-3.0-a9-1/bin/x86_64-pc-linux-gnu# ./lat_sig prot /usr/tmp
mmap: Bad file descriptor
```
I tried my best but failed to figure out the correct way to define the argument [file]. Can anybody help? many thanks!