Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 30 Oct 2023 09:57:03 +0800 | Subject | Re: [PATCH v1] lib,kprobes: using try_cmpxchg_local in objpool_push | From | "wuqiang.matt" <> |
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On 2023/10/30 01:05, Guenter Roeck wrote: > On Mon, Oct 23, 2023 at 07:24:52PM +0800, wuqiang.matt wrote: >> The objpool_push can only happen on local cpu node, so only the local >> cpu can touch slot->tail and slot->last, which ensures the correctness >> of using cmpxchg without lock prefix (using try_cmpxchg_local instead >> of try_cmpxchg_acquire). >> >> Testing with IACA found the lock version of pop/push pair costs 16.46 >> cycles and local-push version costs 15.63 cycles. Kretprobe throughput >> is improved to 1.019 times of the lock version for x86_64 systems. >> >> OS: Debian 10 X86_64, Linux 6.6rc6 with freelist >> HW: XEON 8336C x 2, 64 cores/128 threads, DDR4 3200MT/s >> >> 1T 2T 4T 8T 16T >> lock: 29909085 59865637 119692073 239750369 478005250 >> local: 30297523 60532376 121147338 242598499 484620355 >> 32T 48T 64T 96T 128T >> lock: 957553042 1435814086 1680872925 2043126796 2165424198 >> local: 968526317 1454991286 1861053557 2059530343 2171732306 >> >> Signed-off-by: wuqiang.matt <wuqiang.matt@bytedance.com> > > This patch results in > > lib/objpool.c:169:12: error: implicit declaration of function 'arch_cmpxchg_local' is invalid in C99 > > or > > lib/objpool.c: In function 'objpool_try_add_slot': > include/linux/atomic/atomic-arch-fallback.h:384:27: error: implicit declaration of function 'arch_cmpxchg_local'
This patch was already reverted from probes/for-next by Masami Hiramatsu. Then we will rework it after the arch_cmpxchg_local issue is resolved.
> for various architectures (I have seen it with arc, hexagon, and openrisc > so far). > > As usual, my apologies for the noise if this has already been reported > and/or fixed.
We are working on it and the fix is in discussion.
> Guenter
Regards, wuqiang
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