Hi Kirill,
"Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx> writes:
> On Wed, Feb 14, 2018 at 06:05:01PM -0500, Jan Stancek wrote:
>> Hi,
>>
>> mallocstress[1] LTP testcase takes ~5+ minutes to complete
>> on some arm64 systems (e.g. 4 node, 64 CPU, 256GB RAM):
>> real 7m58.089s
>> user 0m0.513s
>> sys 24m27.041s
>>
>> But if I turn off THP ("transparent_hugepage=never") it's a lot faster:
>> real 0m4.185s
>> user 0m0.298s
>> sys 0m13.954s
>>
>
> It's multi-threaded workload. My *guess* is that poor performance is due
> to lack of ARCH_ENABLE_SPLIT_PMD_PTLOCK support on arm64.
In this instance I think the latency is due to the large size of PMD
hugepages and THP=always. But split PMD locks seem like a useful feature
to have for large core count systems.
I'll have a go at enabling this for arm64.
Thanks,
Punit
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