merge bitehist example

README.md

@@ -38,10 +38,9 @@ Tracing... Hit Ctrl-C to end.
 The above output shows a bimodal distribution, where the largest mode of
 800 I/O was between 128 and 255 Kbytes in size.
 
-See the source: [bitehist.c](examples/tracing/bitehist.c) and
-[bitehist.py](examples/tracing/bitehist.py). What this traces, what this stores, and how
-the data is presented, can be entirely customized. This shows only some of
-many possible capabilities.
+See the source: [bitehist.py](examples/tracing/bitehist.py). What this traces,
+what this stores, and how the data is presented, can be entirely customized.
+This shows only some of many possible capabilities.
 
 ## Installing
 
@@ -60,7 +59,7 @@ pair of .c and .py files, and some are directories of files.
 
 Examples:
 
-- examples/tracing/[bitehist.py](examples/tracing/bitehist.py) examples/tracing/[bitehist.c](examples/tracing/bitehist.c): Block I/O size histogram. [Examples](examples/tracing/bitehist_example.txt).
+- examples/tracing/[bitehist.py](examples/tracing/bitehist.py): Block I/O size histogram. [Examples](examples/tracing/bitehist_example.txt).
 - examples/tracing/[disksnoop.py](examples/tracing/disksnoop.py) examples/tracing/[disksnoop.c](examples/tracing/disksnoop.c): Trace block device I/O latency. [Examples](examples/tracing/disksnoop_example.txt).
 - examples/[hello_world.py](examples/hello_world.py): Prints "Hello, World!" for new processes.
 - examples/tracing/[tcpv4connect.py](examples/tracing/tcpv4connect.py): Trace TCP IPv4 active connections. [Examples](examples/tracing/tcpv4connect_example.txt).

examples/tracing/bitehist.py

@@ -1,7 +1,7 @@
 #!/usr/bin/python
 #
 # bitehist.py	Block I/O size histogram.
-#		For Linux, uses BCC, eBPF. See .c file.
+#		For Linux, uses BCC, eBPF. Embedded C.
 #
 # Written as a basic example of using a histogram to show a distribution.
 #
@@ -17,7 +17,18 @@
 from time import sleep
 
 # load BPF program
-b = BPF(src_file = "bitehist.c")
+b = BPF(text="""
+#include <uapi/linux/ptrace.h>
+#include <linux/blkdev.h>
+
+BPF_HISTOGRAM(dist);
+
+int kprobe__blk_account_io_completion(struct pt_regs *ctx, struct request *req)
+{
+	dist.increment(bpf_log2l(req->__data_len / 1024));
+	return 0;
+}
+""")
 
 # header
 print("Tracing... Hit Ctrl-C to end.")