This patchset adds tracepoints around mmap_lock acquisition. This is useful so
we can measure the latency of lock acquisition, in order to detect contention.
This version is based upon linux-next (since it depends on some recently-merged
patches [1] [2]), and incorporates feedback from the review of the previous
version:
- Functions renamed to reserve the "trace_" prefix for actual tracepoints.
- We no longer measure the duration directly. Instead, users are expected to
construct a synthetic event which computes the interval between "start
locking" and "acquire returned".
- The new helper for checking if tracepoints are enabled in a header is used to
avoid un-inlining any of the lock wrappers. This yields ~zero overhead if the
tracepoints aren't enabled, and therefore obviates the need for a Kconfig for
this change.
[1] https://lore.kernel.org/patchwork/patch/1316922/
[2] https://lore.kernel.org/patchwork/patch/1311996/
Axel Rasmussen (2):
tracing: support "bool" type in synthetic trace events
mmap_lock: add tracepoints around lock acquisition
include/linux/mmap_lock.h | 112 +++++++++++++++++++++++++++---
include/trace/events/mmap_lock.h | 70 +++++++++++++++++++
kernel/trace/trace_events_synth.c | 4 ++
mm/Makefile | 2 +-
mm/mmap_lock.c | 87 +++++++++++++++++++++++
5 files changed, 265 insertions(+), 10 deletions(-)
create mode 100644 include/trace/events/mmap_lock.h
create mode 100644 mm/mmap_lock.c
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2.28.0.806.g8561365e88-goog