Re: [PATCH 0/9] x86/clear_huge_page: multi-page clearing

[Raghavendra K T]

On 4/9/2023 4:16 AM, Ankur Arora wrote:
> Raghavendra K T <raghavendra.kt@xxxxxxx> writes:
>
> > On 4/3/2023 10:52 AM, Ankur Arora wrote:
> > > This series introduces multi-page clearing for hugepages.
>
> >     *Milan*     mm/clear_huge_page   x86/clear_huge_page   change
> >                             (GB/s)           (GB/s)
> >    pg-sz=2MB                 12.24            17.54    +43.30%
> >     pg-sz=1GB                17.98            37.24   +107.11%
> >
> >
> > Hello Ankur,
> >
> > Was able to test your patches. To summarize, am seeing 2x-3x perf
> > improvement for 2M, 1GB base hugepage sizes.
>
> Great. Thanks Raghavendra.
>
> > SUT: Genoa AMD EPYC
> >     Thread(s) per core:  2
> >     Core(s) per socket:  128
> >     Socket(s):           2
> >
> > NUMA:
> >    NUMA node(s):          2
> >    NUMA node0 CPU(s):     0-127,256-383
> >    NUMA node1 CPU(s):     128-255,384-511
> >
> > Test:  Use mmap(MAP_HUGETLB) to demand a fault on 64GB region (NUMA node0), for
> > both base-hugepage-size=2M and 1GB
> >
> > perf stat -r 10 -d -d  numactl -m 0 -N 0 <test>
> >
> > time in seconds elapsed (average of 10 runs) (lower = better)
> >
> > Result:
> > page-size  mm/clear_huge_page   x86/clear_huge_page
> > 2M              5.4567          2.6774
> > 1G              2.64452         1.011281
>
> So translating into BW, for Genoa we have:
>
> page-size  mm/clear_huge_page   x86/clear_huge_page
>   2M              11.74              23.97
>   1G              24.24              63.36
>
> That's a pretty good bump over Milan:
>
> >     *Milan*     mm/clear_huge_page   x86/clear_huge_page
> >                             (GB/s)           (GB/s)
> >    pg-sz=2MB                12.24            17.54
> >    pg-sz=1GB                17.98            37.24
>
> Btw, are these numbers with boost=1?

Yes it is. Also a note about config. I had not enabled
GCOV/LOCKSTAT related config because I faced some issues.