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ring-buffer: More precise timestamps for nested writes

Suresh E. Warrier lkml 1 version In review

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  1. v1 Latest2 patches 5 repliesIn review

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#Subject and filesSizeRepliesApplied
1/2ring-buffer: Introduce precise nested timestamp sysfs attributeDocumentation/trace/ftrace.txt include/linux/ring_buffer.h kernel/trace/ring_buffer.c +1 more+82 -00 replies
2/2More precise timestamps for nested writeskernel/trace/ring_buffer.c+67 -45 replies

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Cover letter [PATCH 0/2] ring-buffer: More precise timestamps for nested writes

This patch set provides supports a way to record precise timestamps for nested writes and a tunable to enable the behavior.

Nested writes occur when a trace writer is preempted, usually through an interrupt and the interrupt handler also writes its own trace. It has been noticed on large systems with lots of interrupts, several hundred trace events can be recorded with the same time stamp.

Fixing this requires a small critical section in the trace write code in which interrupts are disabled. This is an expensive operation for many architectures. Hence, the need for a kernel tunable that allows the feature to be enabled by admins only when needed.

Suresh Warrier (2):
ring-buffer: Introduce precise nested timestamp sysfs attribute
ring-buffer: More precise timestamps for nested writes

 Documentation/trace/ftrace.txt |  8 ++++
 include/linux/ring_buffer.h    |  9 +++++
 kernel/trace/ring_buffer.c     | 85 ++++++++++++++++++++++++++++++++++++++++--
 kernel/trace/trace.c           | 51 +++++++++++++++++++++++++
 4 files changed, 149 insertions(+), 4 deletions(-)
Signature · 1 line
1.8.3.4