tracepoint support for argdist and trace, and new tplist tool for pri…

…nting tracepoints

README.md

@@ -108,6 +108,7 @@ Examples:
 - tools/[tcpconnect](tools/tcpconnect.py): Trace TCP active connections (connect()). [Examples](tools/tcpconnect_example.txt).
 - tools/[tcpconnlat](tools/tcpconnlat.py): Trace TCP active connection latency (connect()). [Examples](tools/tcpconnlat_example.txt).
 - tools/[tcpretrans](tools/tcpretrans.py): Trace TCP retransmits and TLPs. [Examples](tools/tcpretrans_example.txt).
+- tools/[tplist](tools/tplist.py): Display kernel tracepoints and their format.
 - tools/[trace](tools/trace.py): Trace arbitrary functions, with filters. [Examples](tools/trace_example.txt)
 - tools/[vfscount](tools/vfscount.py) tools/[vfscount.c](tools/vfscount.c): Count VFS calls. [Examples](tools/vfscount_example.txt).
 - tools/[vfsstat](tools/vfsstat.py) tools/[vfsstat.c](tools/vfsstat.c): Count some VFS calls, with column output. [Examples](tools/vfsstat_example.txt).

man/man8/argdist.8

@@ -50,11 +50,11 @@ many cases, argdist will deduce the necessary header files automatically.
 .SH SPECIFIER SYNTAX
 The general specifier syntax is as follows:
 
-.B {p,r}:[library]:function(signature)[:type[,type...]:expr[,expr...][:filter]][#label]
+.B {p,r,t}:{[library],category}:function(signature)[:type[,type...]:expr[,expr...][:filter]][#label]
 .TP
-.B {p,r}
-Probe type \- "p" for function entry, "r" for function return;
-\-H for histogram collection, \-C for frequency count.
+.B {p,r,t}
+Probe type \- "p" for function entry, "r" for function return, "t" for kernel
+tracepoint; \-H for histogram collection, \-C for frequency count.
 Indicates where to place the probe and whether the probe should collect frequency
 count information, or aggregate the collected values into a histogram. Counting 
 probes will collect the number of times every parameter value was observed,
@@ -68,12 +68,17 @@ Specify the full path to the .so or executable file where the function to probe
 resides. Alternatively, you can specify just the lib name: for example, "c"
 refers to libc. If no library name is specified, the kernel is assumed.
 .TP
+.B category
+The category of the kernel tracepoint. For example: net, sched, block.
+.TP
 .B function(signature)
 The function to probe, and its signature.
 The function name must match exactly for the probe to be placed. The signature,
 on the other hand, is only required if you plan to collect parameter values 
 based on that signature. For example, if you only want to collect the first
 parameter, you don't have to specify the rest of the parameters in the signature.
+When capturing kernel tracepoints, this should be the name of the event, e.g.
+net_dev_start_xmit. The signature for kernel tracepoints should be empty.
 .TP
 .B [type[,type...]]
 The type(s) of the expression(s) to capture.
@@ -85,6 +90,9 @@ The expression(s) to capture.
 These are the values that are assigned to the histogram or raw event collection.
 You may use the parameters directly, or valid C expressions that involve the
 parameters, such as "size % 10".
+Tracepoints may access a special structure called "tp" that is formatted according
+to the tracepoint format (which you can obtain using tplist). For example, the
+block:block_rq_complete tracepoint can access tp.nr_sector.
 Return probes can use the argument values received by the
 function when it was entered, through the $entry(paramname) special variable.
 Return probes can also access the function's return value in $retval, and the
@@ -137,6 +145,14 @@ Count fork() calls in libc across all processes, grouped by pid:
 #
 .B argdist -C 'p:c:fork():int:$PID;fork per process'
 .TP
+Print histogram of number of sectors in completing block I/O requests:
+#
+.B argdist -H 't:block:block_rq_complete():u32:tp.nr_sector'
+.TP
+Aggregate interrupts by interrupt request (IRQ):
+#
+.B argdist -C 't:irq:irq_handler_entry():int:tp.irq'
+.TP
 Print histograms of sleep() and nanosleep() parameter values:
 #
 .B argdist -H 'p:c:sleep(u32 seconds):u32:seconds' 'p:c:nanosleep(struct timespec *req):long:req->tv_nsec'

man/man8/tplist.8

@@ -0,0 +1,39 @@
+.TH tplist 8 "2016-03-20" "USER COMMANDS"
+.SH NAME
+tplist \- Display kernel tracepoints and their format.
+.SH SYNOPSIS
+.B tplist [-v] [tracepoint]
+.SH DESCRIPTION
+tplist lists all kernel tracepoints, and can optionally print out the tracepoint
+format; namely, the variables that you can trace when the tracepoint is hit. This
+is usually used in conjunction with the argdist and/or trace tools.
+
+On a typical system, accessing the tracepoint list and format requires root.
+.SH OPTIONS
+.TP
+\-v
+Display the variables associated with the tracepoint or tracepoints.
+.TP
+[tracepoint]
+A wildcard expression that specifies which tracepoints to print. For example,
+block:* will print all block tracepoints (block:block_rq_complete, etc.).
+Regular expressions are not supported.
+.SH EXAMPLES
+.TP
+Print all kernel tracepoints:
+#
+.B tplist
+.TP
+Print all net tracepoints with their format:
+#
+.B tplist -v 'net:*'
+.SH SOURCE
+This is from bcc.
+.IP
+https://github.com/iovisor/bcc
+.SH OS
+Linux
+.SH STABILITY
+Unstable - in development.
+.SH AUTHOR
+Sasha Goldshtein

man/man8/trace.8

@@ -45,10 +45,12 @@ information. See PROBE SYNTAX below.
 The general probe syntax is as follows:
 
 .B [{p,r}]:[library]:function [(predicate)] ["format string"[, arguments]]
+
+.B t:category:event [(predicate)] ["format string"[, arguments]]
 .TP
-.B [{p,r}]
-Probe type \- "p" for function entry, "r" for function return. The default
-probe type is "p".
+.B {[{p,r}],t}
+Probe type \- "p" for function entry, "r" for function return, "t" for kernel
+tracepoint. The default probe type is "p".
 .TP
 .B [library]
 Library containing the probe.
@@ -58,9 +60,15 @@ refers to libc. If no library name is specified, the kernel is assumed. Also,
 you can specify an executable name (without a full path) if it is in the PATH.
 For example, "bash".
 .TP
+.B category
+The tracepoint category. For example, "sched" or "irq".
+.TP
 .B function
 The function to probe.
 .TP
+.B event
+The tracepoint event. For example, "block_rq_complete".
+.TP
 .B [(predicate)]
 The filter applied to the captured data. Only if the filter evaluates as true,
 the trace message will be printed. The filter can use any valid C expression
@@ -81,6 +89,11 @@ number of arguments as there are placeholders in the format string. The
 format specifier replacements may be any C expressions, and may refer to the
 same special keywords as in the predicate (arg1, arg2, etc.).
 
+In tracepoints, both the predicate and the arguments may refer to the tracepoint
+format structure, which is stored in the special "tp" variable. For example, the
+block:block_rq_complete tracepoint can print or filter by tp.nr_sector. To 
+discover the format of your tracepoint, use the tplist tool.
+
 The predicate expression and the format specifier replacements for printing
 may also use the following special keywords: $pid, $tgid to refer to the 
 current process' pid and tgid; $uid, $gid to refer to the current user's
@@ -102,6 +115,10 @@ Trace all malloc calls and print the size of the requested allocation:
 Trace returns from the readline function in bash and print the return value as a string:
 #
 .B trace 'r:bash:readline """%s"", retval' 
+.TP
+Trace the block:block_rq_complete tracepoint and print the number of sectors completed:
+#
+.B trace 't:block:block_rq_complete """%d sectors"", tp.nr_sector'
 .SH SOURCE
 This is from bcc.
 .IP

src/python/bcc/__init__.py

@@ -325,6 +325,11 @@ def open_kprobes():
  global open_kprobes
  return open_kprobes
 
+ @staticmethod
+ def open_uprobes():
+ global open_uprobes
+ return open_uprobes
+
  @staticmethod
  def detach_kprobe(event):
  ev_name = "p_" + event.replace("+", "_").replace(".", "_")