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.m...@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
