Linux Plumbers Conference Tracing Summit 2012 Interoperability - - PowerPoint PPT Presentation

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Linux Plumbers Conference Tracing Summit 2012 Interoperability - - PowerPoint PPT Presentation

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Linux Plumbers Conference Tracing Summit 2012 Interoperability Between Tracing Tools with the Common Trace Format (CTF) E-mail: mathieu.desnoyers@efficios.com Mathieu Desnoyers August 30th, 2012 1 > Presenter Mathieu Desnoyers

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August 30th, 2012 Mathieu Desnoyers 1

Linux Plumbers Conference Tracing Summit 2012

Interoperability Between Tracing Tools with the Common Trace Format (CTF) E-mail: mathieu.desnoyers@efficios.com

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August 30th, 2012 Mathieu Desnoyers 2

> Presenter

  • Mathieu Desnoyers
  • EfficiOS Inc.
  • http://www.efficios.com
  • Author/Maintainer of
  • LTTng, LTTng-UST, Babeltrace, Userspace RCU
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August 30th, 2012 Mathieu Desnoyers 3

> Content

  • Common Trace Format introduction & goals
  • Trace Stream Description Language
  • Overview of trace layout
  • Collaboration
  • Reference implementations
  • Other tools based on CTF
  • Areas to improve
  • Conclusion
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August 30th, 2012 Mathieu Desnoyers 4

> Common Trace Format

  • Targets system-wide and multi-system trace

representation in a common format, for integrated analysis:

  • Software traces

– Across multiple CPUs – Across the software stack (Hypervisor, kernel,

library, applications)

  • Hardware traces

– DSPs, device-specific tracing components. – GPUs.

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August 30th, 2012 Mathieu Desnoyers 5

> Goals of the Common Trace Format (CTF)

  • Portable,
  • Compact,
  • Configurable per-architecture to express layout

required for speed,

  • Transport independent: disk, network, serial

port, memory,

  • Usable on minimalistic DSPs as well as full-

featured OS,

  • Availability of flight recorder,
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August 30th, 2012 Mathieu Desnoyers 6

> Goals of the Common Trace Format (CTF) (continued)

  • Buffers retrievable after crash,
  • Support dynamically inserted instrumentation

while tracing,

  • Support per-cpu buffers, and many configurable

streams.

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August 30th, 2012 Mathieu Desnoyers 7

> What is CTF ?

  • Self-described binary trace format
  • Domain-specific language (DSL) for description
  • f stream layout: TSDL (Trace Stream

Description Language)

  • Trace embeds its own description
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August 30th, 2012 Mathieu Desnoyers 8

> TSDL Trace Description

  • TSDL trace description entry:

trace { major = 1; minor = 8; uuid = "a116db0a-ad45-40a0-9f66-b195d79432a0"; byte_order = le; packet_header := struct { uint32_t magic; uint8_t uuid[16]; uint32_t stream_id; }; };

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August 30th, 2012 Mathieu Desnoyers 9

> TSDL Clock Description

  • TSDL clock description entry:

clock { name = monotonic; uuid = "1fece6ff-a288-4a59-b750-07bef0d296f0"; description = "Monotonic Clock"; freq = 1000000000; /* Frequency, in Hz */ /* clock value offset from Epoch is: offset * (1/freq) */

  • ffset = 1338755739325858212;

}; typealias integer { size = 64; align = 8; signed = false; map = clock.monotonic.value; } := uint64_clock_monotonic_t;

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August 30th, 2012 Mathieu Desnoyers 10

> TSDL Types

  • TSDL type descriptions:

typealias integer { size = 64; align = 8; signed = false; } := uint64_t; [...] typealias integer { size = 27; align = 1; signed = false; } := uint27_t; struct packet_context { uint64_clock_monotonic_t timestamp_begin; uint64_clock_monotonic_t timestamp_end; uint32_t events_discarded; uint32_t content_size; uint32_t packet_size; uint32_t cpu_id; }; struct event_header { uint64_t timestamp; uint32_t id; } align(8);

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August 30th, 2012 Mathieu Desnoyers 11

> TSDL Stream and Event

  • TSDL stream and event descriptions:

stream { id = 0; event.header := struct event_header; packet.context := struct packet_context; }; event { name = "ust_tests_hello:tptest"; id = 0; stream_id = 0; loglevel = 13; fields := struct { uint27_t _intfield; [...] }; };

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August 30th, 2012 Mathieu Desnoyers 12

> CTF Diagram: Field Types

Enumeration Array Sequence Float Structure Integer String Depends on Variant

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August 30th, 2012 Mathieu Desnoyers 13

> CTF Diagram: Event Structure Example

Header id timestamp Event Context vpid procname Payload field0 field1

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August 30th, 2012 Mathieu Desnoyers 14

> CTF Diagram: Trace Structure

Metadata typealias ...; trace { ... }; clock { ...}; stream { ... }; event { ... }; Packet 0 header context event 0 event 1 ... Packet 1 header context event 0 event 1 ... ... Stream 0 Packet 0 header context event 0 event 1 ... Packet 1 header context event 0 event 1 ... ... Stream 1 ...

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August 30th, 2012 Mathieu Desnoyers 15

> CTF Diagram: Trace Structure

/ Trace directory hierarchy:

metadata

... stream_1 stream_0

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August 30th, 2012 Mathieu Desnoyers 16

> CTF Diagram: Trace Collection

/ Trace collection directory hierarchy:

metadata

... stream_1 stream_0 TraceA TraceB ...

metadata

... stream_1 stream_0 Check if clock UUID match for trace correlation.

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August 30th, 2012 Mathieu Desnoyers 17

> Advanced Usage: Variant Type

struct event_header_compact { enum : uint5_t { compact = 0 ... 30, extended = 31 } id; variant <id> { struct { uint27_clock_monotonic_t timestamp; } compact; struct { uint32_t id; uint64_clock_monotonic_t timestamp; } extended; } v; } align(8);

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August 30th, 2012 Mathieu Desnoyers 18

> Advanced Usage: Variant Type (2)

8 32 16 8 ... 15 0 ... 7 24...31 16...23 8 32 16 id (32-bit) 8 ... 15 0 ... 7 24...31 16...23 31 timestamp (27-bit) vpid (32-bit) event fields... timestamp (64-bit) vpid (32-bit) event fields... id 3-bit padding: on this architecture, 32-bit and 64-bit integers are aligned

  • n 8-bit.

5-bit: value 31 selects “extended” variant. 5-bit: values 0-30 select “compact” variant.

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August 30th, 2012 Mathieu Desnoyers 19

> Environment Description

env { hostname = "thinkos"; domain = "kernel"; sysname = "Linux"; kernel_release = "3.4-trunk-amd64"; kernel_version = "#1 SMP Tue Jun 26 17:23:03 UTC 2012"; tracer_name = "lttng-modules"; tracer_major = 2; tracer_minor = 0; tracer_patchlevel = 1; };

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August 30th, 2012 Mathieu Desnoyers 20

> Collaboration

  • Trace format specification
  • Funded by

– Linux Foundation CE Linux Forum and Ericsson

  • In collaboration with Multi-Core Association Tool

Infrastructure Workgroup

– Freescale, Mentor Graphics, IBM, IMEC, National

Instruments, Nokia Siemens Networks, Samsung, Texas Instruments, Tilera, Wind River, University of Houston, Polytechnique Montréal, University of Utah.

  • Gathered feedback from Linux kernel

developers and SystemTAP communities.

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August 30th, 2012 Mathieu Desnoyers 21

> Reference Implementations

  • Babeltrace
  • Reference implementation trace conversion tool

and read/seek API for trace collections.

  • Initially converts

– From CTF to text – From dmesg text log to CTF

  • LTTng kernel 2.0 and LTTng-UST 2.0
  • Native CTF producer reference implementation.
  • Eclipse Tracing and Monitoring Framework
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August 30th, 2012 Mathieu Desnoyers 22

> Other tools based on CTF

  • GDB (coming in Q4 2012)
  • Javeltrace (CTF generator)
  • Proprietary converters (derived from

Babeltrace)

  • LTTngTop
  • LTTV
  • LTTng Studio
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August 30th, 2012 Mathieu Desnoyers 23

> Areas to Improve

  • Support for clocks with varying frequency,
  • Mandate some of the currently “suggested”

fields,

  • Extend CTF to include state change description

along with events,

  • Extend CTF to include categorization of events,
  • Should we keep CTF minimalistic (limited to

description of binary layout and clocks), or include high-level semantic information ?

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August 30th, 2012 Mathieu Desnoyers 24

> Questions ?

?

  • http://www.efficios.com
  • LTTng Information
  • http://lttng.org
  • lttng-dev@lists.lttng.org
  • CTF specification available at:

http://www.efficios.com/ctf