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Message-ID: <20090109001341.6ea77e98@daedalus.pq.iki.fi> Date: Fri, 9 Jan 2009 00:13:41 +0200 From: Pekka Paalanen <pq@....fi> To: Steven Rostedt <rostedt@...dmis.org> Cc: Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org>, linux-kernel <linux-kernel@...r.kernel.org>, pq@....fi Subject: [PATCH v2 1/3] doc: mmiotrace.txt, buffer size control change >From 297ddd1d79f7826bdd058b1bfd580dcaf97d3946 Mon Sep 17 00:00:00 2001 From: Pekka Paalanen <pq@....fi> Date: Sat, 3 Jan 2009 21:09:27 +0200 Subject: [PATCH] doc: mmiotrace.txt, buffer size control change Impact: prevents confusing the user when buffer size is inadequate The tracing framework offers a resizeable buffer, which mmiotrace uses to record events. If the buffer is full, the following events will be lost. Events should not be lost, so the documentation instructs the user to increase the buffer size. The buffer size is set via a debugfs file. Mmiotrace documentation was not updated the same time the debugfs file was changed. The old file was tracing/trace_entries and first contained the number of entries the buffer had space for, per cpu. Nowadays this file is replaced with the file tracing/buffer_size_kb, which tells the amount of memory reserved for the buffer, per cpu, in kilobytes. Previously, a flag had to be toggled via the debugfs file tracing/tracing_enabled when the buffer size was changed. This is no longer necessary. The mmiotrace documentation is updated to reflect the current state of the tracing framework. Signed-off-by: Pekka Paalanen <pq@....fi> --- Documentation/tracers/mmiotrace.txt | 6 ++---- 1 files changed, 2 insertions(+), 4 deletions(-) diff --git a/Documentation/tracers/mmiotrace.txt b/Documentation/tracers/mmiotrace.txt index cde23b4..5731c67 100644 --- a/Documentation/tracers/mmiotrace.txt +++ b/Documentation/tracers/mmiotrace.txt @@ -78,12 +78,10 @@ to view your kernel log and look for "mmiotrace has lost events" warning. If events were lost, the trace is incomplete. You should enlarge the buffers and try again. Buffers are enlarged by first seeing how large the current buffers are: -$ cat /debug/tracing/trace_entries +$ cat /debug/tracing/buffer_size_kb gives you a number. Approximately double this number and write it back, for instance: -$ echo 0 > /debug/tracing/tracing_enabled -$ echo 128000 > /debug/tracing/trace_entries -$ echo 1 > /debug/tracing/tracing_enabled +$ echo 128000 > /debug/tracing/buffer_size_kb Then start again from the top. If you are doing a trace for a driver project, e.g. Nouveau, you should also -- 1.6.0.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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