code: def read_mmap(fd, sz):
      with Timing("mmfd:       ", lambda x: f", {sz/x:.2f} GB/s"):
          buf = mmap.mmap(
              fd, sz, flags=mmap.MAP_SHARED | mmap.MAP_POPULATE
          )  # |MAP_LOCKED)
          t = 0
          for i in range(0, sz, 0x1000):
              t += buf[i]
  
file_path: tinygrad/extra/disk_read_speed.py
imports: import os, ctypes, ctypes.util, io, mmap
  from tinygrad import Tensor, dtypes, Device
  from tinygrad.helpers import Timing, from_mv
  from tinygrad.runtime.ops_hip import HIPDevice
label_desc: Use image node_id 2 for calling a global function with example usage: read_mmap(fd, sz) without return types