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Filename Latest commit message Latest commit date
Levi Yun 598b156722 trace/trace_event_perf: remove duplicate samples on the first tracepoint event
[ Upstream commit afe5960dc208fe069ddaaeb0994d857b24ac19d1 ]

When a tracepoint event is created with attr.freq = 1,
'hwc->period_left' is not initialized correctly. As a result,
in the perf_swevent_overflow() function, when the first time the event occurs,
it calculates the event overflow and the perf_swevent_set_period() returns 3,
this leads to the event are recorded for three duplicate times.

Step to reproduce:
    1. Enable the tracepoint event & starting tracing
         $ echo 1 > /sys/kernel/tracing/events/module/module_free
         $ echo 1 > /sys/kernel/tracing/tracing_on

    2. Record with perf
         $ perf record -a --strict-freq -F 1 -e "module:module_free"

    3. Trigger module_free event.
         $ modprobe -i sunrpc
         $ modprobe -r sunrpc

Result:
     - Trace pipe result:
         $ cat trace_pipe
         modprobe-174509  [003] .....  6504.868896: module_free: sunrpc

     - perf sample:
         modprobe  174509 [003]  6504.868980: module:module_free: sunrpc
         modprobe  174509 [003]  6504.868980: module:module_free: sunrpc
         modprobe  174509 [003]  6504.868980: module:module_free: sunrpc

By setting period_left via perf_swevent_set_period() as other sw_event did,
This problem could be solved.

After patch:
     - Trace pipe result:
         $ cat trace_pipe
         modprobe 1153096 [068] 613468.867774: module:module_free: xfs

     - perf sample
         modprobe 1153096 [068] 613468.867794: module:module_free: xfs

Link: https://lore.kernel.org/20240913021347.595330-1-yeoreum.yun@arm.com
Fixes: bd2b5b1284 ("perf_counter: More aggressive frequency adjustment")
Signed-off-by: Levi Yun <yeoreum.yun@arm.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-12-14 19:44:28 +01:00
arch ARM: dts: cubieboard4: Fix DCDC5 regulator constraints 2024-12-14 19:44:24 +01:00
block blk-rq-qos: fix crash on rq_qos_wait vs. rq_qos_wake_function race 2024-11-08 16:20:48 +01:00
certs
crypto crypto: pcrypt - Call crypto layer directly when padata_do_parallel() return -EBUSY 2024-12-14 19:44:23 +01:00
Documentation dt-bindings: vendor-prefixes: Add NeoFidelity, Inc 2024-12-14 19:44:25 +01:00
drivers drm/etnaviv: hold GPU lock across perfmon sampling 2024-12-14 19:44:27 +01:00
fs hfsplus: don't query the device logical block size multiple times 2024-12-14 19:44:22 +01:00
include netpoll: Use rcu_access_pointer() in netpoll_poll_lock 2024-12-14 19:44:28 +01:00
init initramfs: avoid filename buffer overrun 2024-12-14 19:44:21 +01:00
ipc
kernel trace/trace_event_perf: remove duplicate samples on the first tracepoint event 2024-12-14 19:44:28 +01:00
lib debugobjects: Fix conditions in fill_pool() 2024-11-08 16:20:34 +01:00
LICENSES
mm mm: revert "mm: shmem: fix data-race in shmem_getattr()" 2024-12-14 19:44:19 +01:00
net net: rfkill: gpio: Add check for clk_enable() 2024-12-14 19:44:27 +01:00
samples bpf: Fix the xdp_adjust_tail sample prog issue 2024-12-14 19:44:26 +01:00
scripts kbuild: Use uname for LINUX_COMPILE_HOST detection 2024-12-14 19:44:19 +01:00
security security/keys: fix slab-out-of-bounds in key_task_permission 2024-11-17 14:58:50 +01:00
sound ALSA: 6fire: Release resources at card release 2024-12-14 19:44:27 +01:00
tools selftests: net: really check for bg process completion 2024-12-14 19:44:27 +01:00
usr
virt KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin() 2024-11-08 16:20:47 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore Remove *.orig pattern from .gitignore 2024-11-08 16:20:33 +01:00
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.286 2024-11-17 14:58:53 +01:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
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Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.