[PATCH] Update documentation

Some of it was a little out of sync with reality. Add an example for live
tracing, locally as well as over the network.

diff --git a/README b/README
index 3c323dd2c2a9c04f485ead8e5f86986bc7111de6..80f4a5184ff22b71c5171df9c0d1d56c952e2701 100644 (file)
--- a/README
+++ b/README
@@ -17,30 +17,45 @@ rsync://rsync.kernel.org/pub/scm/linux/kernel/git/axboe/blktrace.git
 Usage
 -----
 
-To run:
-       % blktrace -d <dev> [-a <trace> [-a <trace>]]
-               -a <trace> is one of: (use multiple -a options to get more)
-                       READ
-                       WRITE
-                       BARRIER
-                       SYNC
-                       QUEUE
-                       REQUEUE
-                       ISSUE
-                       COMPLETE
-                       FS
-                       PC
+% blktrace -d <dev> [-o <output> -a <trace> [-a <trace>]]
+       -a <trace> is one of: (use multiple -a options to get more)
+               READ
+               WRITE
+               BARRIER
+               SYNC
+               QUEUE
+               REQUEUE
+               ISSUE
+               COMPLETE
+               FS
+               PC
        --- run task to generate load to be traced ---
        <SIGINT to kill>
        --- Generates:
-               <dev>_dat.[0..ncpus] : Contains binary pdu data
-               <dev>_out.[0..ncpus] : Contains binary trace data
+               <output>_out.[0..ncpus] : Contains binary trace data
 
-       % blkparse <dev>
+       % blkparse -i <input> [-o <output>]
        --- Generates:
-               <dev>_log.[0..ncpus] : Contains formatted trace data
+               <output>_log.[0..ncpus] : Contains formatted trace data, if
+               output logging is added with the -o option.
                Merged formatted trace data to stdout
 
 
-20050826, Jens Axboe <axboe@suse.de>
+If you want to do live tracing, you can pipe the data between blktrace
+and blkparse:
+
+% blktrace -d <device> -o - | blkparse -i -
+
+This has a small risk of displaying some traces a little out of sync, since
+it will do batch sorts of input events. Similarly, you can do traces over
+the network with eg netcat:
+
+% blktrace -d /dev/sda -o - | netcat parsehost portno
+% netcat tracehost portno | blkparse -i -
+
+Which will send the traces from tracehost to parsehost over the network on
+the defined port number.
+
+
+20050906, Jens Axboe <axboe@suse.de>