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Subject[PATCH v3 1/3] docs: ftrace: Clarify the RAM impact of buffer_size_kb
The current text could mislead the user into believing that the number
of pages allocated by each CPU ring buffer is calculated by the round
up of the division: buffer_size_kb / PAGE_SIZE.

Clarifies that a few extra pages may be allocated to accommodate buffer
management meta-data.

Suggested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Suggested-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Frank A. Cancio Bello <frank@generalsoftwareinc.com>
---
Documentation/trace/ftrace.rst | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst
index d2b5657ed33e..5a037bedbf6a 100644
--- a/Documentation/trace/ftrace.rst
+++ b/Documentation/trace/ftrace.rst
@@ -185,7 +185,8 @@ of ftrace. Here is a list of some of the key files:
CPU buffer and not total size of all buffers. The
trace buffers are allocated in pages (blocks of memory
that the kernel uses for allocation, usually 4 KB in size).
- If the last page allocated has room for more bytes
+ A few extra pages may be allocated to accommodate buffer management
+ meta-data. If the last page allocated has room for more bytes
than requested, the rest of the page will be used,
making the actual allocation bigger than requested or shown.
( Note, the size may not be a multiple of the page size
--
2.17.1
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