#!/usr/sbin/dtrace -s

string Xrequest[uintptr_t];

Xserver*:::request-start
/Xrequest[arg0] == ""/
{
    Xrequest[arg0] = copyinstr(arg0);
}

Xserver*:::request-start
{
    reqstart = vtimestamp;    
}

Xserver*:::request-done
{
    @times[Xrequest[arg0]] = avg(vtimestamp - reqstart);
}