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authorPekka Paalanen <pq@iki.fi>2009-01-03 21:09:27 +0200
committerIngo Molnar <mingo@elte.hu>2009-02-15 20:05:13 +0100
commitf9aa28adfc6a4b01268ebb6d88566cca8627905f (patch)
tree20890c68a824dbca558425878856d865e1d85ccf /Documentation
parent6bc5c366b1a45ca18fba6851f62db5743b3f6db5 (diff)
downloadop-kernel-dev-f9aa28adfc6a4b01268ebb6d88566cca8627905f.zip
op-kernel-dev-f9aa28adfc6a4b01268ebb6d88566cca8627905f.tar.gz
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@iki.fi> Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/tracers/mmiotrace.txt6
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
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