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author | Steven Rostedt <srostedt@redhat.com> | 2012-08-03 20:10:49 (GMT) |
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committer | Steven Rostedt <rostedt@goodmis.org> | 2013-03-15 04:34:44 (GMT) |
commit | 277ba04461c2746cf935353474c0961161951b68 (patch) | |
tree | df2b8eb157c6725e606605f6acf40acbd4f13dd6 /block | |
parent | 12ab74ee00d154bc05ea2fc659b7ce6519e5d5a6 (diff) | |
download | linux-fsl-qoriq-277ba04461c2746cf935353474c0961161951b68.tar.xz |
tracing: Add interface to allow multiple trace buffers
Add the interface ("instances" directory) to add multiple buffers
to ftrace. To create a new instance, simply do a mkdir in the
instances directory:
This will create a directory with the following:
# cd instances
# mkdir foo
# ls foo
buffer_size_kb free_buffer trace_clock trace_pipe
buffer_total_size_kb set_event trace_marker tracing_enabled
events/ trace trace_options tracing_on
Currently only events are able to be set, and there isn't a way
to delete a buffer when one is created (yet).
Note, the i_mutex lock is dropped from the parent "instances"
directory during the mkdir operation. As the "instances" directory
can not be renamed or deleted (created on boot), I do not see
any harm in dropping the lock. The creation of the sub directories
is protected by trace_types_lock mutex, which only lets one
instance get into the code path at a time. If two tasks try to
create or delete directories of the same name, only one will occur
and the other will fail with -EEXIST.
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'block')
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