Messages in this thread | | | Date | Wed, 09 Jun 2021 18:04:57 -0400 | From | Steven Rostedt <> | Subject | [PATCH 0/2] tracing: Simplify and document the trace event filtering temp buffer code |
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When filtering trace events, a temp buffer is used because the extra copy from the temp buffer into the ring buffer is still faster than the direct write into the ring buffer followed by a discard if the filter does not match.
But the data that can be stored in the temp buffer is a PAGE_SIZE minus the ring buffer event header. The calculation of that header size is complex, but using the helper macro "struct_size()" can simplify it.
Also, add more documentation about what is going on.
Link: https://lore.kernel.org/stable/CAHk-=whKbJkuVmzb0hD3N6q7veprUrSpiBHRxVY=AffWZPtxmg@mail.gmail.com/
Steven Rostedt (VMware) (2): tracing: Simplify the max length test when using the filtering temp buffer tracing: Add better comments for the filtering temp buffer use case
---- kernel/trace/trace.c | 40 ++++++++++++++++++++++++++++++++++++++-- 1 file changed, 38 insertions(+), 2 deletions(-)
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