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Qing Wang fb2671376b perf/core: Fix broken throttling when max_samples_per_tick=1 
[ Upstream commit f51972e6f8 ]

According to the throttling mechanism, the pmu interrupts number can not
exceed the max_samples_per_tick in one tick. But this mechanism is
ineffective when max_samples_per_tick=1, because the throttling check is
skipped during the first interrupt and only performed when the second
interrupt arrives.

Perhaps this bug may cause little influence in one tick, but if in a
larger time scale, the problem can not be underestimated.

When max_samples_per_tick = 1:
Allowed-interrupts-per-second max-samples-per-second  default-HZ  ARCH
200                           100                     100         X86
500                           250                     250         ARM64
...
Obviously, the pmu interrupt number far exceed the user's expect.

Fixes: e050e3f0a7 ("perf: Fix broken interrupt rate throttling")
Signed-off-by: Qing Wang <wangqing7171@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250405141635.243786-3-wangqing7171@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2025-06-27 11:05:10 +01:00
arch um: let 'make clean' properly clean underlying SUBARCH as well 2025-06-04 14:38:08 +02:00
block block: fix direct io NOWAIT flag not work 2025-05-22 14:08:26 +02:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:22:01 +02:00
crypto crypto: algif_hash - fix double free in hash_accept 2025-06-04 14:38:05 +02:00
Documentation x86/bugs: Make spectre user default depend on MITIGATION_SPECTRE_V2 2025-06-04 14:37:59 +02:00
drivers thunderbolt: Do not double dequeue a configuration request 2025-06-27 11:05:09 +01:00
fs gfs2: gfs2_create_inode error handling fix 2025-06-27 11:05:09 +01:00
include tpm: tis: Double the timeout B to 4s 2025-06-04 14:38:08 +02:00
init sched/isolation: Make CONFIG_CPU_ISOLATION depend on CONFIG_SMP 2025-05-02 07:44:36 +02:00
io_uring io_uring: fix possible deadlock in io_register_iowq_max_workers() 2024-11-17 15:06:25 +01:00
ipc ipc/sem: Fix dangling sem_array access in semtimedop race 2022-12-08 11:28:45 +01:00
kernel perf/core: Fix broken throttling when max_samples_per_tick=1 2025-06-27 11:05:10 +01:00
lib crypto: lzo - Fix compression buffer overrun 2025-06-04 14:37:58 +02:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm mm/page_alloc.c: avoid infinite retries caused by cpuset race 2025-06-04 14:38:06 +02:00
net net_sched: hfsc: Address reentrant enqueue adding class to eltree twice 2025-06-04 14:38:07 +02:00
samples samples/bpf: Fix compilation failure for samples/bpf on LoongArch Fedora 2025-06-04 14:37:54 +02:00
scripts kbuild: fix argument parsing in scripts/config 2025-06-04 14:37:57 +02:00
security smack: recognize ipv4 CIPSO w/o categories 2025-06-04 14:38:02 +02:00
sound ALSA: pcm: Fix race of buffer access at PCM OSS layer 2025-06-04 14:38:06 +02:00
tools bpftool: Fix readlink usage in get_fd_type 2025-06-04 14:38:04 +02:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:27:15 +01:00
virt KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin() 2024-10-22 15:40:41 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Remove *.orig pattern from .gitignore 2024-10-17 15:11:10 +02:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS trace: Relocate event helper files 2024-04-10 16:19:24 +02:00
Makefile Linux 5.15.185 2025-06-04 14:38:08 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

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

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
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.