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Subject[PATCH v5 2/2] perf record: Update docs regarding the maximum limitation of AUX area
Date
The maximum AUX area is limited by the page size of the system. Update
the documentation to reflect this.

Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
---
tools/perf/Documentation/perf-record.txt | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 680396c56bd1..dfc322d6f1f1 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -292,6 +292,17 @@ OPTIONS
Also, by adding a comma, the number of mmap pages for AUX
area tracing can be specified.

+ The maximum AUX area is limited by the maximum physically contiguous
+ memory allocated from slab/slub. It can be calculated with following
+ formula:
+
+ PAGE_SIZE << MAX_ORDER
+ ( ---------------------- ) * PAGE_SIZE
+ sizeof(page_pointer)
+
+ For example with 4K pages and MAX_ORDER=10 configured, the maximum AUX
+ area is 2GiB.
+
-g::
Enables call-graph (stack chain/backtrace) recording for both
kernel space and user space.
--
2.39.3
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