Hi Wuqiang, I dug my mail box and found this. Sorry for replying late.
On Tue, 5 Sep 2023 09:52:50 +0800 "wuqiang.matt" <wuqiang.m...@bytedance.com> wrote: > This patch series introduces a scalable and lockless ring-array based > object pool and replaces the original freelist (a LIFO queue based on > singly linked list) to improve scalability of kretprobed routines. > > v9: > 1) objpool: raw_local_irq_save/restore added to prevent interruption > > To avoid possible ABA issues, we must ensure objpool_try_add_slot > and objpool_try_add_slot are uninterruptible. If these operations > are blocked or interrupted in the middle, other cores could overrun > the same slot's ages[] of uint32, then after resuming back, the > interrupted pop() or push() could see same value of ages[], which > is a typical ABA problem though the possibility is small. > > The pair of pop()/push() costs about 8.53 cpu cycles, measured > by IACA (Intel Architecture Code Analyzer). That is, on a 4Ghz > core dedicated for pop() & push(), theoretically it would only > need 8.53 seconds to overflow a 32bit value. Testings upon Intel > i7-10700 (2.90GHz) cost 71.88 seconds to overrun a 32bit integer. What does this mean? This sounds like "There is a timing issue if it's enough fast". Let me reivew the patch itself. Thanks, > > 2) codes improvements: thanks to Masami for the thorough inspection > > v8: > 1) objpool: refcount added for objpool lifecycle management > > wuqiang.matt (5): > lib: objpool added: ring-array based lockless MPMC > lib: objpool test module added > kprobes: kretprobe scalability improvement with objpool > kprobes: freelist.h removed > MAINTAINERS: objpool added > > MAINTAINERS | 7 + > include/linux/freelist.h | 129 -------- > include/linux/kprobes.h | 11 +- > include/linux/objpool.h | 174 ++++++++++ > include/linux/rethook.h | 16 +- > kernel/kprobes.c | 93 +++--- > kernel/trace/fprobe.c | 32 +- > kernel/trace/rethook.c | 90 +++-- > lib/Kconfig.debug | 11 + > lib/Makefile | 4 +- > lib/objpool.c | 338 +++++++++++++++++++ > lib/test_objpool.c | 689 +++++++++++++++++++++++++++++++++++++++ > 12 files changed, 1320 insertions(+), 274 deletions(-) > delete mode 100644 include/linux/freelist.h > create mode 100644 include/linux/objpool.h > create mode 100644 lib/objpool.c > create mode 100644 lib/test_objpool.c > > -- > 2.40.1 > -- Masami Hiramatsu (Google) <mhira...@kernel.org>
