linux-kernel - Re: [BUG] perf sched broken

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Date:	Wed, 12 Jan 2011 10:11:13 -0200
From:	Arnaldo Carvalho de Melo <acme@...radead.org>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	Peter Zijlstra <peterz@...radead.org>, mingo@...e.hu,
	Robert Richter <robert.richter@....com>,
	Mike Galbraith <efault@....de>,
	Corey Ashford <cjashfor@...ux.vnet.ibm.com>
Subject: Re: [BUG] perf sched broken

Em Wed, Jan 12, 2011 at 10:29:05AM +0100, Stephane Eranian escreveu:
> Hi,
> 
> I am trying to use perf sched from tip-x86 but it fails for all my attempts.
> 
> First of, I think the event list is stale. This is not so much the
> events themselves
> but rather the flags.
> 
> Looks to me like the :r modifier is not supported anymore, so a patch like the
> one below is needed. That helps collect a trace. But then, you can dump
> the trace.

I got to this point as well, and reverting 4c635a4 did the trick for me,
Corey, this is another report for that problem, can you take a look at
it? Stephane, can you try doing a:

git show 4c635a4 | patch -p1 -R

To see if the problem is fixed?

- Arnaldo
 
> $ perf sched rec dd if=/dev/zero of=/dev/null count=1000000
> 1000000+0 records in
> 1000000+0 records out
> 512000000 bytes (512 MB) copied, 0.589981 s, 868 MB/s
> [ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 0.481 MB perf.data (~20997 samples) ]
> 
> $ perf sched rep
> run measurement overhead: 2934 nsecs
> sleep measurement overhead: 90502 nsecs
> the run test took 999149 nsecs
> the sleep test took 1092248 nsecs
>   Fatal: no trace data in the file
> 
> $ perf sched trace -D
>  usage: perf sched [<options>] {record|latency|map|replay|trace}
> 
>     -i, --input <file>    input file name
>     -v, --verbose         be more verbose (show symbol address, etc)
>     -D, --dump-raw-trace  dump raw trace in ASCII
> 
> Note that this is not specific to pref sched. If I use perf record directly,
> I run into the same issue:
> $ perf record -R -a -c 1 -e sched:sched_switch -- sleep 1
> [ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 0.365 MB perf.data (~15962 samples) ]
> $./perf report -D
>   Fatal: no trace data in the file
> 
> Now that perf trace is gone, how to I dump the trace?

Good question, checking this s/trace/script/g fallout.

- Arnaldo
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