On 2020/8/20 下午10:02, Pekka Enberg wrote: > On Mon, Aug 10, 2020 at 3:18 PM Xunlei Pang <xlpang@xxxxxxxxxxxxxxxxx> wrote: >> >> v1->v2: >> - Improved changelog and variable naming for PATCH 1~2. >> - PATCH3 adds per-cpu counter to avoid performance regression >> in concurrent __slab_free(). >> >> [Testing] >> On my 32-cpu 2-socket physical machine: >> Intel(R) Xeon(R) CPU E5-2650 v2 @ 2.60GHz >> perf stat --null --repeat 10 -- hackbench 20 thread 20000 >> >> == original, no patched >> 19.211637055 seconds time elapsed ( +- 0.57% ) >> >> == patched with patch1~2 >> Performance counter stats for 'hackbench 20 thread 20000' (10 runs): >> >> 21.731833146 seconds time elapsed ( +- 0.17% ) >> >> == patched with patch1~3 >> Performance counter stats for 'hackbench 20 thread 20000' (10 runs): >> >> 19.112106847 seconds time elapsed ( +- 0.64% ) >> >> >> Xunlei Pang (3): >> mm/slub: Introduce two counters for partial objects >> mm/slub: Get rid of count_partial() >> mm/slub: Use percpu partial free counter >> >> mm/slab.h | 2 + >> mm/slub.c | 124 +++++++++++++++++++++++++++++++++++++++++++------------------- >> 2 files changed, 89 insertions(+), 37 deletions(-) > > We probably need to wrap the counters under CONFIG_SLUB_DEBUG because > AFAICT all the code that uses them is also wrapped under it. /sys/kernel/slab/***/partial sysfs also uses it, I can wrap it with CONFIG_SLUB_DEBUG or CONFIG_SYSFS for backward compatibility. > > An alternative approach for this patch would be to somehow make the > lock in count_partial() more granular, but I don't know how feasible > that actually is. > > Anyway, I am OK with this approach: > > Reviewed-by: Pekka Enberg <penberg@xxxxxxxxxx> Thanks! > > You still need to convince Christoph, though, because he had > objections over this approach. Christoph, what do you think, or any better suggestion to address this *in production* issue? > > - Pekka >
