style updates

man/man8/biosnoop.8

@@ -12,6 +12,9 @@ the I/O was first created (which usually identifies the responsible process).
 This uses in-kernel eBPF maps to cache process details (PID and comm) by I/O
 request, as well as a starting timestamp for calculating I/O latency.
 
+This works by tracing various kernel blk_*() functions using dynamic tracing,
+and will need updating to match any changes to these functions.
+
 This makes use of a Linux 4.5 feature (bpf_perf_event_output());
 for kernels older than 4.5, see the version under tools/old,
 which uses an older mechanism

tools/biosnoop.py

@@ -138,6 +138,7 @@ class Data(ct.Structure):
 start_ts = 0
 prev_ts = 0
 delta = 0
+
 # process event
 def print_event(cpu, data, size):
  event = ct.cast(data, ct.POINTER(Data)).contents
@@ -169,6 +170,7 @@ def print_event(cpu, data, size):
  prev_ts = event.ts
  start_ts = 1
 
+# loop with callback to print_event
 b["events"].open_perf_buffer(print_event)
 while 1:
  b.kprobe_poll()