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Table of Contents
Meeting Notes
November 12, 2014
Were present:
- Dominique Toupin
- Agustin Vega-Frias
- Mathieu Desnoyers
- Christian Babeux
- Masami Hiramatsu
- Christoph Lameter
- Thomas Gleixner
- Petru Lauric
- Ed Martinez
- (and others we for which we missed the name)
Diamon Introduction
- Dominique introduce the reason why the workgroup was created.
- Current diamon draft is largely based on Linux in telecom companies (Ericsson), other requirements welcomed.
- Overview of website, share information with other companies and user.
Overview of mini-coredumps
- Linutronix
- Trigger memory dump when application crash.
- Dump only a small portion of memory instead of the whole memory.
- Configurable, setup watches, per application fine tuning.
- Libminicoredump, apps can register data structures to be dumped.
- Capture state of application
- Snapshot in time, asynchronous dump to debug
- Plan is to host the mini core dump at diamon.org
How to integrate mini-coredump with tracing? Snapshot? → Application registration mechanism with mini-coredump
How to integrate those tools? Distribution to users and packaging not ready.
Overview of TraceCompass (UI for Linux tracing)
- Import text logs, libpcap traces, LTTng traces
- Show information from mini-coredump
- Standalone application similar to Wireshark
How to integrate this standalone tool in another toolkit? → Java based toolkit should be easy
- Used by Intel for trace tool, Sourcery Analyser from Mentor, etc.
Overview of the reason for the creation of the workgroup
- In tracing, everyone is scratching their own itch, workgroup a reason to share and collaborate together
- LTTng project is focusing on trace analysis, usable by non-expert (e.g. non-kernel developers)
- CTF, a trace format to be able to correlate multiple tracing data sources
Christoph Lameter: Finding latencies in their own applications. Multiple tools, difficult to use. Get user feedback on what they would like to see in those tools.
Interest from perf/ftrace to CTF?
Linutronix + Red Hat, perf to CTF module, work is on-going. Post-processing perf output file to convert to CTF. Mostly functional, few rough-edges, still need to modify Eclipse viewer to adapt to the event semantic exposed by Perf.
People asking for the presentation from Jiri Olsa at this year tracing summit. http://www.tracingsummit.org/w/images/9/98/TracingSummit2014-Perf-CTF.pdf
Steven Rostedt from ftrace interested in looking into CTF.
Masami: Where can the CTF specification be found ? CTF specification available at http://www.efficios.com/ctf Eventually, the plan is to move the specification to the Diamon workgroup. Babeltrace and libbabeltrace can be used to convert/read CTF.
Work on Common Trace Clocks
Thomas Gleixner:
- Provide a NMI-safe accessor to the clock monotonic. Provides a clock that can be correlated with user-space monotonic clock.
- Correlated timestamp across the network possible.
- Merged in 3.17
How to use this clock ?
- extern u64 ktime_get_mono_fast_ns(void);
- Can change the clock in ftrace, via debugfs.
- Perf still has to figure out how to expose this.
- use clock monotonic: give correlation across network, which is harder to do when using directly TSC.
- Correlation between clock monotonic and clock realtime can be done with a single correlation point, since both clocks are adjusted in the same way by NTP.
HW assisted tracing
Freescale:
- Trace from the cpu, hw port, ETM/PTM like trace.
- HW trace form SoC, DDR controllers
- At tracing summit, presented tool for soc trace, for network developers
- Issue about having a common clock, traces from multiple hw, different hw clocks
- How to correlate with hardware and software traces
- Hw trace tend to be proprietary, need for common generic format.
- Consuming CTF file, analysis in TraceCompass
- DMTF format to CTF?
- Could probably use babeltrace to convert. Semantic about the clocks could be missing from DMTF though.
The diamon workgroup is a lean workgroup, straightforward governance. Do not need to be a member of LF to join, If you want your company logo on diamon.org (this is optional), send the request to Mike Dolan <mdolan at linuxfoundation.org>
How to correspond with diamon? “Diamon discuss” mailing list. https://lists.linuxfoundation.org/mailman/listinfo/diamon-discuss
Next meeting: Contribution from other users to see what they would like to be improved in tooling.
Christoph Lameter: will bring someone from his team to present Masami Hiramatsu: Interested in cloud logging/tracing. Integration of app logging with tracing.
