From: Punit Agrawal <punit.agrawal@arm.com>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Jan Stancek <jstancek@redhat.com>,
linux-mm@kvack.org, lwoodman <lwoodman@redhat.com>,
Rafael Aquini <aquini@redhat.com>,
Andrea Arcangeli <aarcange@redhat.com>
Subject: Re: [bug?] mallocstress poor performance with THP on arm64 system
Date: Fri, 16 Feb 2018 17:30:19 +0000 [thread overview]
Message-ID: <87a7w84zbo.fsf@e105922-lin.cambridge.arm.com> (raw)
In-Reply-To: <20180215090246.qrsnncq3ajtbdlfy@node.shutemov.name> (Kirill A. Shutemov's message of "Thu, 15 Feb 2018 12:02:46 +0300")
Hi Kirill,
"Kirill A. Shutemov" <kirill@shutemov.name> 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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next prev parent reply other threads:[~2018-02-16 17:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1523287676.1950020.1518648233654.JavaMail.zimbra@redhat.com>
2018-02-14 23:05 ` Jan Stancek
2018-02-15 9:02 ` Kirill A. Shutemov
2018-02-16 17:30 ` Punit Agrawal [this message]
2018-02-15 18:40 ` Punit Agrawal
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