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Subject: Re: [PATCH 4/5] x86: entry_64.S: always allocate complete "struct pt_regs"
From: "H. Peter Anvin" <hpa@zytor.com>
Date: Sat, 02 Aug 2014 14:23:04 -0700
To: Andy Lutomirski <luto@amacapital.net>
CC: Denys Vlasenko <vda.linux@googlemail.com>,
        Denys Vlasenko <dvlasenk@redhat.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Oleg Nesterov <oleg@redhat.com>,
        Frederic Weisbecker <fweisbec@gmail.com>, X86 ML <x86@kernel.org>,
        Alexei Starovoitov <ast@plumgrid.com>, Will Drewry <wad@chromium.org>,
        Kees Cook <keescook@chromium.org>
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It would be nice to automate running a T-test on it.

On August 2, 2014 2:14:50 PM PDT, Andy Lutomirski <luto@amacapital.net> wrote:
>On Fri, Aug 1, 2014 at 3:13 PM, H. Peter Anvin <hpa@zytor.com> wrote:
>> On 08/01/2014 03:11 PM, Denys Vlasenko wrote:
>>>>
>>>> Could you please try to see if there is a measurable change in the
>>>> latency of a trivial syscall?
>>>
>>> Will do.
>>> Something along the lines of "how long does it take to execute two
>>> gazillions of getppid()?"
>>>
>>
>> Something like that, yes, but you have to run enough data points so
>you
>> can determine if the difference is statistically significant or just
>noise.
>
>Denys, if you want to avoid five minutes of programming, you can build
>this:
>
>https://gitorious.org/linux-test-utils/linux-clock-tests/
>
>and run timing_test_64 10 getpid
>
>It doesn't do real statistics, but it seems to get quite stable
>results.
>
>--Andy

-- 
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