Re: Support for Perf CTF traces now in master (was Re: FW: [RFC 0/5] perf tools: Add perf data CTF conversion)

[Alexandre Montplaisir <alexmonthy@voxpopuli.im>]

On 2014-11-26 12:37 PM, Sebastian Andrzej Siewior wrote:
> * Alexandre Montplaisir | 2014-11-12 17:14:45 [-0500]:
>
>> Just a quick note, this branch is now merged to master. So anyone who
>> pulls the code from the master branch at
>> git://git.eclipse.org/gitroot/tracecompass/org.eclipse.tracecompass.git
>> should be able to load perf-CTF traces in the viewer. The trace type
>> is now called "Common Trace Format -> Linux Kernel Trace" and should
>> support both LTTng kernel and perf traces in CTF format (although
>> auto-detection should work in most cases).
> Thank you for all the work.
> Let me try to reply to the emails at once here:
> - I added to the environment metadata the following (comparing to the
>    last version):
>     domain => kernel
>     tracer_name => perf
>
>    There is no tracer_major + minor. Instead I added
>        version => perf's version
>    On my system I have:
>       release = "3.16.0-4-amd64";
>       version = "3.18.rc3.g91405a";
>
>    Because I run Debian's v3.16 and recorded the trace with perf from the
>    kernel 3.18.rc3.
>    There is no version of perf doing the convert of perf.data => ctf.
>    Any objections, rename of the version member?
>
> - Mathieu decided that it makes no sense to add the kernel version to
>    each event we trace. Instead each event should have its own version
>    with a major/minor member. Once the event is changed the "ABI"
>    version should be adjusted. I second this since it makes sense.
>    Therefore there are no changes that were made to the converter.
>
> - Alexandre (you) noticed that there are syscall names in the events
>    recorded via "sys_enter and sys_exit". This is true, but there is a
>    hint. There is an event for instance:
>
> [03:37:07.579969498] (+?.?????????) raw_syscalls:sys_enter: { cpu_id = 2 }, { perf_ip = 0xFFFFFFFF81020EBC, perf_tid = 30004, perf_pid = 30004, perf_id = 382, perf_period = 1, common_type = 76, common_flags = 0, common_preempt_count = 0, common_pid = 30004, id = 16, args = [ [0] = 0xE, [1] = 0x2400, [2] = 0x0, [3] = 0x0, [4] = 0xA20F00, [5] = 0xA1FDA0 ] }

Oh ok, so this "id" field is really the system call ID then. Good to 
know, thanks!

>
>    By the end you notice id=16 and args. args are the Arguments passed
>    to syscall and id is the syscall number. Together with machine =
>    x86_64 you know which architecture you need to lookup the number 16.
>    The numbers are from unistd.h (and may be different between architectures,
>    even between i386 & x86_64). strace has for instance the following [0] table.
>
> { 3,    TD, sys_read,       "read"      },  /* 0 */
> …
> { 3,    TD, sys_ioctl,      "ioctl"     },  /* 16 */
> …
>
> So 16 is ioctl. strace has those tables for a bunch of architectures
> so it might be helpful to suck them in. I know no other way to ease
> things here.

Indeed. Well this information could be part of the trace metadata too, 
but I guess that wouldn't be very practical.
We'll just need to add a way for each supported tracer to advertize how 
it gets its system call names.

>
> [0] https://github.com/bnoordhuis/strace/blob/master/linux/x86_64/syscallent.h
>
> The same thing is true for softirq_entry events for instance. This event
> will give you you only vec=9 and you need to lookup that 9 => RCU. That
> one is easy however:
>
>   const char * const softirq_to_name[NR_SOFTIRQS] = {
>           "HI", "TIMER", "NET_TX", "NET_RX", "BLOCK", "BLOCK_IOPOLL",
>           "TASKLET", "SCHED", "HRTIMER", "RCU"
>   };
>
> this has been taken from kernel/softirq.c.

Oh, that's right, we never got around to getting/showing the actual 
names of the soft IRQs. Thanks for reminding us. ;)

>> This was based on the most recent file format I was aware of, we will
>> update it accordingly if required.
>>
>> Testing welcome!
> I pushed the perf changes I mentioned to
>
>    git://git.breakpoint.cc/bigeasy/linux.git ctf_convert_7
>
> It is now based on Arnaldo's perf/core. If everything goes well from
> the compass side and nobody complains here in any way, the next step
> would be to present the patches on the mailing list and compass as a
> user.
>
> I took you tree and added the patch below. I uploaded the following
> files to https://breakpoint.cc/perf-ctf/:
> - ctf-out6.tar.xz from perf6.data.xz
>    shows nothing

Hmm, indeed it throws exceptions in the console when trying to validate 
the trace. It seems to read a packet size in perf_stream_0 as a negative 
value. Babeltrace handles it fine though, so we're probably reading it 
wrong. We'll investigate.

Cheers,
Alexandre

>
> - ctf-out7.tar.xz from perf7.data.xz
>    shows something
>
> The only obvious difference is the size of the CTF data. The size of out6
> is almost 300MiB and it contains 3,259,929 events. The out7 is has only
> 15MiB and contains 152,900 events.
>
>> Cheers,
>> Alexandre
> ✂
>
>  From 7ffa619d918f2010046b391ae29063ffc5329468 Mon Sep 17 00:00:00 2001
> From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Date: Wed, 26 Nov 2014 18:04:53 +0100
> Subject: [PATCH] CTF: use tracer_name for perf-CTF traces
>
> domain will be set to kernel for both, perf and lttng traces. The
> tracer_name will be set to perf if the trace is generated by perf and
> otherwise lttng-modules if created by thet lttng tool.
>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
>   .../tracecompass/lttng2/kernel/core/trace/LttngKernelTrace.java      | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/org.eclipse.tracecompass.lttng2.kernel.core/src/org/eclipse/tracecompass/lttng2/kernel/core/trace/LttngKernelTrace.java b/org.eclipse.tracecompass.lttng2.kernel.core/src/org/eclipse/tracecompass/lttng2/kernel/core/trace/LttngKernelTrace.java
> index a58269f..03a09b9 100644
> --- a/org.eclipse.tracecompass.lttng2.kernel.core/src/org/eclipse/tracecompass/lttng2/kernel/core/trace/LttngKernelTrace.java
> +++ b/org.eclipse.tracecompass.lttng2.kernel.core/src/org/eclipse/tracecompass/lttng2/kernel/core/trace/LttngKernelTrace.java
> @@ -96,12 +96,11 @@ public class LttngKernelTrace extends CtfTmfTrace {
>            * metadata
>            */
>           Map<String, String> traceEnv = this.getCTFTrace().getEnvironment();
> -        String domain = traceEnv.get("domain"); //$NON-NLS-1$
>           String tracerName = traceEnv.get("tracer_name"); //$NON-NLS-1$
>           String tracerMajor = traceEnv.get("tracer_major"); //$NON-NLS-1$
>           String tracerMinor = traceEnv.get("tracer_minor"); //$NON-NLS-1$
>   
> -        if ("\"kernel-perf\"".equals(domain)) { //$NON-NLS-1$
> +        if ("\"perf\"".equals(tracerName)) { //$NON-NLS-1$
>               fOriginTracer = OriginTracer.PERF;
>   
>           } else if ("\"lttng-modules\"".equals(tracerName) && //$NON-NLS-1$
> @@ -130,7 +129,7 @@ public class LttngKernelTrace extends CtfTmfTrace {
>               CTFTrace temp = new CTFTrace(path);
>               /* Make sure the domain is "kernel" in the trace's env vars */
>               String dom = temp.getEnvironment().get("domain"); //$NON-NLS-1$
> -            if (dom != null && dom.startsWith("\"kernel")) { //$NON-NLS-1$
> +            if (dom != null && dom.equals("\"kernel\"")) { //$NON-NLS-1$
>                   return new TraceValidationStatus(CONFIDENCE, Activator.PLUGIN_ID);
>               }
>               return new Status(IStatus.ERROR, Activator.PLUGIN_ID, Messages.LttngKernelTrace_DomainError);