Messages in this thread | | | From | "wuqiang.matt" <> | Subject | [PATCH v9 0/5] lib,kprobes: kretprobe scalability improvement | Date | Tue, 5 Sep 2023 09:52:50 +0800 |
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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.
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
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