linux-kernel - Re: futex testsuite suggestion...

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Date:	Mon, 27 Oct 2014 13:29:14 -0700
From:	Darren Hart <dvhart@...ux.intel.com>
To:	David Miller <davem@...emloft.net>
CC:	linux-kernel@...r.kernel.org, Darren Hart <dvhart@...radead.org>
Subject: Re: futex testsuite suggestion...

On 10/27/14 12:56, David Miller wrote:
> 
> First of all, thanks so much for writing your futex test suite, it's
> proved invaluable for sparc64 kernel development for me lately.

Hi David,

Glad to hear it :-)

> 
> I'd like to suggest that you add a test that triggers transparent
> hugepages, because if an architecture doesn't implement
> __get_user_pages_fast() such futexes cause a machine to hang.
> 
> I hacked up something simple that took the existing performance
> test and made it operate in a register allocated using memalign().
> 
> I would suggest doing a memalign(HUGEPAGE_SIZE, HUGEPAGE_SIZE) then
> iterating running a futex test within each normal page within that
> hugepage.

Do you want this option for the performance tests, or would a less
intensive functional test be sufficient?

The other thing to note is there have been several efforts/false starts
to get futextests into perf and kselftest. We currently considering
splitting futextests across the two (performance to perf, functional to
kselftest). The TODO for a fuzz tester is handled *more* than adequately
by trinity.

I'm perfectly happy to add such a test. I'm currently buried under a
number of other things that have resulted in futextests suffering
somewhat. So a couple of things to help make this happen:

1) Could you send me your hacked up test, in whatever condition?
2) I'm more than happy to accept patches, but I do understand why you
might prefer to have someone else write it :-)

Thanks,

-- 
Darren Hart
Intel Open Source Technology Center
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